diff --git a/mods/bambu/bambu.js b/mods/bambu/bambu.js
index 3b1a3bd6..53117cc3 100644
--- a/mods/bambu/bambu.js
+++ b/mods/bambu/bambu.js
@@ -37,7 +37,8 @@ self.kiri.load(api => {
                 let { serial, message, error } = data;
                 if (error) {
                     console.log({ serial, error });
-                    printer_status(`error: ${error}`);
+                    api.alerts.show(`Bambu Error: ${error}`, 3);
+                    // printer_status(`error: ${error}`);
                 } else if (serial) {
                     let rec = status[serial] = deepMerge(status[serial] || {}, message);
                     if (selected?.rec.serial === serial) {
@@ -176,9 +177,14 @@ self.kiri.load(api => {
         $('bbl_bed_target').value = bed_target_temper?.toFixed(1) ?? '';
         if (files) {
             h.bind($('bbl_files'), files.map(file => {
+                let name = file.name
+                    .toLowerCase()
+                    .replace('.gcode','')
+                    .replace('.3mf','');
                 return h.option({
-                    _: file.name || file,
-                    style: "max-width: 20em"
+                    _: name,
+                    style: "max-width: 20em",
+                    value:`${file.path}${file.name}`
                 });
             }));
             rec.files = undefined;
@@ -196,7 +202,7 @@ self.kiri.load(api => {
         $('bbl_status').value = msg;
     }
 
-    function render_list() {
+    function render_list(to) {
         let list = Object.keys(printers).map(name => {
             return h.option({ _: name, value: name })
         });
@@ -204,7 +210,7 @@ self.kiri.load(api => {
             h.option({ _: '', value: '' }),
             ...list
         ]
-        h.bind(select, list);
+        h.bind(to || select, list);
     }
 
     function monitor_start(rec) {
@@ -421,26 +427,35 @@ self.kiri.load(api => {
         }
     });
 
-    function sendok(params = {}) {
-        host = password = serial = amsmap = undefined;
-        const { settings } = params;
-        const ams = settings.device?.gcodePre.filter(line => line.indexOf(defams) === 0)[0];
-        if (ams) {
-            try {
-                amsmap = ams.substring(defams.length).trim().replaceAll(' ','');
-            } catch (e) {
-                console.log({ invalid_ams_map: ams });
-            }
+    function prep_export(gen3mf, gcode, info, settings) {
+        if (!settings.device.extras?.bbl) {
+            $('bambu-output').style.display = 'none';
+            return;
         }
-        const feature = settings.device?.gcodePre.filter(line => line.indexOf(defhost) === 0)[0];
-        if (feature) {
-            [ host, password, serial ] = feature.substring(defhost.length).split(' ').map(v => v.trim());
-            console.log('BAMBU', { host , password, serial });
-            if (host && password) {
-                return true;
-            }
+        printers = settings.device.extras.bbl;
+        let devlist = $('print-bambu-device');
+        render_list(devlist);
+        $('bambu-output').style.display = 'flex';
+        $('print-bambu').onclick = function() {
+            gen3mf(zip => send(`${$('print-filename').value}.3mf`, zip));
         }
-        return false;
+        devlist.onchange = () => {
+            let info = printers[devlist.value];
+            console.log({ selected: devlist.value, info });
+            host = info.host;
+            serial = info.serial;
+            password = info.code;
+            $('print-bambu').disabled = (host && serial && password) ? false : true;
+            const ams = settings.device?.gcodePre.filter(line => line.indexOf(defams) === 0)[0];
+            if (ams) {
+                try {
+                    amsmap = ams.substring(defams.length).trim().replaceAll(' ','');
+                } catch (e) {
+                    console.log({ invalid_ams_map: ams });
+                }
+            }
+            console.log({ bambu: host, serial, amsmap });
+        };
     }
 
     function send(filename, gcode) {
@@ -479,5 +494,5 @@ self.kiri.load(api => {
 
     setInterval(monitor_keepalive, 5000);
 
-    api.bambu = { send, sendok, amsmap };
+    api.bambu = { send, amsmap, prep_export };
 });
diff --git a/mods/bambu/init.js b/mods/bambu/init.js
index 42e8793f..d7639ed0 100644
--- a/mods/bambu/init.js
+++ b/mods/bambu/init.js
@@ -145,8 +145,16 @@ module.exports = async (server) => {
     async function ftp_list(args = {}) {
         const client = await ftp_open(args);
         const list = [];
-        try { list.push(...(await client.list())) } catch (e) { }
-        try { list.push(...(await client.list("/cache"))) } catch (e) { }
+        try {
+            let files = await client.list();
+            files.forEach(file => file.path = "/");
+            list.push(...files);
+         } catch (e) { }
+        try {
+            let files = await client.list("/cache");
+            files.forEach(file => file.path = "/cache/");
+            list.push(...files);
+        } catch (e) { }
         client.close();
         return list;
     }
@@ -193,7 +201,8 @@ module.exports = async (server) => {
             const { host, password, filename, serial, ams } = query;
             const ams_mapping = ams ? ams.split(',').map(v => parseInt(v)) : undefined;
             const mqtt_conn = serial ? get_mqtt(host, password, serial, message => {
-                util.log('mqtt_recv', JSON.parse(message.toString()));
+                util.log('mqtt_recv', message);
+                // util.log('mqtt_recv', JSON.parse(message.toString()));
             }) : undefined;
             ftp_send({ host, password, filename, data })
                 .then(() => {
@@ -271,6 +280,7 @@ module.exports = async (server) => {
                             .filter(file => file.name.toLowerCase().endsWith(".3mf"))
                             .map(file => {
                                 return {
+                                    path: file.path,
                                     name: file.name,
                                     size: file.size,
                                     date: file.rawModifiedAt
diff --git a/src/geo/polygon.js b/src/geo/polygon.js
index e48a63f2..8e722fca 100644
--- a/src/geo/polygon.js
+++ b/src/geo/polygon.js
@@ -2037,7 +2037,7 @@ class Polygon {
             tree = new PolyTree(),
             sp1 = this.toClipper(),
             sp2 = poly.toClipper(),
-            minarea = min >= 0 ? min : 0.1;
+            minarea = min ?? 0.1;
 
         clip.AddPaths(sp1, PathSubject, true);
         clip.AddPaths(sp2, PathClip, true);
diff --git a/src/geo/polygons.js b/src/geo/polygons.js
index 57d1ce77..cf6c411f 100644
--- a/src/geo/polygons.js
+++ b/src/geo/polygons.js
@@ -431,7 +431,7 @@ function subtract(setA, setB, outA, outB, z, minArea, opt = {}) {
      let lpre = length(polys);
 
      if (opt.wasm && geo.wasm) {
-         let min = minarea || 0.01;
+         let min = minarea ?? 0.01;
          // let deepLength = polys.map(p => p.deepLength).reduce((a,v) => a+v);
          // if (deepLength < 15000)
          try {
@@ -632,7 +632,7 @@ function offset(polys, dist, opts = {}) {
         let coff = new ClipperOffset(opts.miter, opts.arc),
             tree = new PolyTree();
 
-        // setup offset
+            // setup offset
         for (let poly of polys) {
             // convert to clipper format
             poly = poly.toClipper();
diff --git a/src/kiri-mode/cam/client.js b/src/kiri-mode/cam/client.js
index e6abff07..2dc4032d 100644
--- a/src/kiri-mode/cam/client.js
+++ b/src/kiri-mode/cam/client.js
@@ -1467,6 +1467,7 @@ CAM.init = function(kiri, api) {
         offover: 'camTraceOffOver',
         dogbone: 'camTraceDogbone',
         revbone: 'camTraceDogbone',
+        merge:   'camTraceMerge',
         select:  'camTraceMode'
     }).inputs = {
         tool:     UC.newSelect(LANG.cc_tool, {}, "tools"),
@@ -1483,6 +1484,7 @@ CAM.init = function(kiri, api) {
         thru:     UC.newInput(LANG.cc_thru_s, {title:LANG.cc_thru_l, convert:UC.toFloat, units:true}),
         offover:  UC.newInput(LANG.cc_offd_s, {title:LANG.cc_offd_l, convert:UC.toFloat, units:true, show:() => poppedRec.offset !== "none"}),
         sep:      UC.newBlank({class:"pop-sep", modes:MCAM, xshow:zDogSep}),
+        merge:    UC.newBoolean(LANG.co_merg_s, undefined, {title:LANG.co_merg_l}),
         bottom:   UC.newBoolean(LANG.cf_botm_s, undefined, {title:LANG.cf_botm_l, show:(op,conf) => conf.process.camZBottom}),
         dogbone:  UC.newBoolean(LANG.co_dogb_s, undefined, {title:LANG.co_dogb_l, show:canDogBones}),
         revbone:  UC.newBoolean(LANG.co_dogr_s, undefined, {title:LANG.co_dogr_l, show:canDogBonesRev}),
diff --git a/src/kiri-mode/cam/driver.js b/src/kiri-mode/cam/driver.js
index 5f6d498c..fd50abc1 100644
--- a/src/kiri-mode/cam/driver.js
+++ b/src/kiri-mode/cam/driver.js
@@ -69,6 +69,7 @@ kiri.load(api => {
             kiri.client.send("cam_traces", { settings, single }, output => {
                 const ids = [];
                 kiri.codec.decode(output).forEach(rec => {
+console.log({ rec });
                     ids.push(rec.id);
                     widgets[rec.id].traces = rec.traces;
                 });
diff --git a/src/kiri-mode/cam/ops.js b/src/kiri-mode/cam/ops.js
index 56448fea..05d014a7 100644
--- a/src/kiri-mode/cam/ops.js
+++ b/src/kiri-mode/cam/ops.js
@@ -1090,6 +1090,7 @@ class OpTrace extends CamOp {
                 poly2polyEmit(polys, newPoint(0,0,0), (poly, index, count, spoint) => {
                     routed.push(poly);
                 });
+                let output = [];
                 for (let poly of POLY.nest(routed)) {
                     let offdist = offset !== 'none' ? offover : 0;
                     if (!offdist)
@@ -1116,15 +1117,24 @@ class OpTrace extends CamOp {
                             zto -= zThru;
                         }
                         for (let z of base.util.lerp(zTop, zto, down)) {
-                            followZ(pi.clone().setZ(z));
+                            output.push(pi.clone().setZ(z));
                         }
                     } else {
                         if (thru) {
                             pi.setZ(pi.getZ() - thru);
                         }
-                        followZ(pi);
+                        output.push(pi);
                     }
                 }
+                // merge overlapping output to prevent overcuts
+                if (op.merge) {
+                    let nest = POLY.nest(output);
+                    let union = POLY.union(nest, 0, true);
+                    output = POLY.flatten(union, [], true);
+                }
+                for (let poly of output) {
+                    followZ(poly);
+                }
                 break;
             case "clear":
                 const zbo = widget.track.top - widget.track.box.d;
diff --git a/src/kiri-mode/cam/slice.js b/src/kiri-mode/cam/slice.js
index c33402fc..df8612de 100644
--- a/src/kiri-mode/cam/slice.js
+++ b/src/kiri-mode/cam/slice.js
@@ -365,7 +365,7 @@ CAM.traces = async function(settings, widget, single) {
                 let trace = traces[i];
                 let dz = Math.abs(z - trace.getZ());
                 // only compare polys farther apart in Z
-                if (dz < 0.01) {
+                if (dz > 0.01) {
                     continue;
                 }
                 // do not add duplicates
diff --git a/src/kiri/export.js b/src/kiri/export.js
index 65c1672b..e08b34e6 100644
--- a/src/kiri/export.js
+++ b/src/kiri/export.js
@@ -477,8 +477,7 @@ function exportGCodeDialog(gcode, sections, info, names) {
         $('code-preview-head').style.display = preview ? '' : 'none';
         $('code-preview').style.display = preview ? '' : 'none';
         $('print-download').onclick = download;
-        $('print-filament-head').style.display = fdm ? '' : 'none';
-        $('print-filament-info').style.display = fdm ? '' : 'none';
+        $('print-filament').style.display = fdm ? '' : 'none';
         $('print-filename').value = filename;
         $('print-filesize').value = util.comma(info.bytes);
         $('print-filament').value = Math.round(info.distance);
@@ -523,10 +522,10 @@ function exportGCodeDialog(gcode, sections, info, names) {
         download3MF.onclick = function() {
             gen3mf(zip => api.util.download(zip, `${$('print-filename').value}.3mf`));
         };
-        let downloadBambu = $('print-bambu');
-        downloadBambu.style.display = api.bambu && api.bambu.sendok({ gcode, info, settings }) ? 'flex' : 'none';
-        downloadBambu.onclick = function() {
-            gen3mf(zip => api.bambu.send(`${$('print-filename').value}.3mf`, zip));
+
+        // present bambu print options when selected device is bambu
+        if (api.bambu) {
+            api.bambu.prep_export(gen3mf, gcode, info, settings);
         }
 
         function gen3mf(then) {
diff --git a/web/kiri/index.css b/web/kiri/index.css
index cb9473d6..ac9c4fdc 100644
--- a/web/kiri/index.css
+++ b/web/kiri/index.css
@@ -107,7 +107,7 @@ button {
     cursor: pointer;
     text-transform: capitalize;
 }
-button:hover {
+button:not([disabled]):hover {
     background-color: var(--main-color);
     color: white;
 }
@@ -118,6 +118,9 @@ button[load] {
 button[del] {
     margin-left: 5px;
 }
+button[disabled] {
+    color: #999;
+}
 input {
     background-color: #f8f8ff;
     margin-bottom: 1px;
@@ -225,6 +228,9 @@ details[open] > summary::after {
 }
 
 /** dark conversion */
+.dark button[disabled] {
+    color: #888;
+}
 .dark input[disabled] {
     border-color: #666;
     background-color: #444;
@@ -250,7 +256,7 @@ details[open] > summary::after {
     background-color: #555;
     border: 1px solid #777;
 }
-button:hover {
+.dark button:not([disabled]):hover {
     background-color: var(--blue-2);
     color: black;
 }
@@ -670,6 +676,9 @@ button:hover {
 .basis-50 {
     flex-basis: 50%;
 }
+.grow0 {
+    flex-grow: 0 !important;
+}
 .grow {
     flex-grow: 1;
 }
@@ -1633,7 +1642,7 @@ button:hover {
     background-color: rgba(255,255,255,0.5);
     border: 1px solid #bbb;
     border-radius: 3px;
-    padding: 20px 10px 10px 10px;
+    padding: 12px 10px 10px 10px;
 }
 .mod-print .box select {
     min-width: 10em;
@@ -1695,9 +1704,10 @@ button:hover {
     display: none;
 }
 #code-preview-textarea {
-    width: 40em;
-    height: 12em;
-    font-size: smaller;
+    min-width: 50em;
+    width: 100%;
+    height: 7em;
+    font-size: x-small;
     font-family: Courier,monospace;
     white-space: nowrap;
     resize: none;
diff --git a/web/kiri/index.html b/web/kiri/index.html
index fbd1379c..a8c3dfe4 100644
--- a/web/kiri/index.html
+++ b/web/kiri/index.html
@@ -583,19 +583,25 @@
         <div id="mod-local" class="mdialog f-col"></div>
         <!-- export dialogs -->
         <div id="mod-x-any" class="mod-print mdialog f-col">
-            <div class="header"><label>export</label></div>
-            <div id="print-info" class="f-col box">
-                <div><label>file name</label><input id="print-filename" size="20" spellcheck="false" /></div>
-                <div><label>file size (bytes)</label><input id="print-filesize" size="12" disabled="true" /></div>
-                <div><label>time estimate (h:m:s)</label><input id="output-time" size="12" disabled="true" /></div>
+            <div class="f-row gap4">
+                <div class="f-col grow">
+                    <div class="header"><label>job</label></div>
+                    <div id="print-info" class="f-col box">
+                        <div><label>file name</label><input id="print-filename" size="20" spellcheck="false" /></div>
+                        <div><label>file size (bytes)</label><input id="print-filesize" size="12" disabled="true" /></div>
+                        <div><label>time estimate (h:m:s)</label><input id="output-time" size="12" disabled="true" /></div>
+                    </div>
+                </div>
+                <div id="print-filament" class="f-col">
+                    <div class="header"><label>material</label></div>
+                    <div class="f-col box">
+                        <div><label>filament density (g/cm^3)</label><input id="print-density" size="12" value="1.25" /></div>
+                        <div><label>filament used (mm)</label><input id="print-filament" size="12" disabled="true" /></div>
+                        <div><label>printed weight (g)</label><input id="print-weight" size="12" disabled="true" /></div>
+                    </div>
+                </div>
             </div>
-            <div id="print-filament-head" class="header"><label>filament</label></div>
-            <div id="print-filament-info" class="f-col box">
-                <div><label>filament density (g/cm^3)</label><input id="print-density" size="12" value="1.25" /></div>
-                <div><label>filament used (mm)</label><input id="print-filament" size="12" disabled="true" /></div>
-                <div><label>printed weight (g)</label><input id="print-weight" size="12" disabled="true" /></div>
-            </div>
-            <div id="code-preview-head" class="header"><label>preview</label></div>
+            <div id="code-preview-head" class="header"><label>gcode preview</label></div>
             <div id="code-preview" class="f-col box">
                 <div><textarea id="code-preview-textarea"></textarea></div>
             </div>
@@ -605,7 +611,14 @@
                 <button id="print-palette" class="grow">palette</button>
                 <button id="print-zip" class="grow">zip</button>
                 <button id="print-3mf" class="grow">3mf</button>
-                <button id="print-bambu" class="grow">bambu</button>
+            </div>
+            <div id="bambu-output" class="f-col">
+                <div class="header"><label>send to bambu</label></div>
+                <div class="f-row box gap4 a-center">
+                    <label class="grow0">printer</label>
+                    <select id="print-bambu-device"></select>
+                    <button id="print-bambu" class="grow" disabled>send job</button>
+                </div>
             </div>
             <div id="send-to-octohead" class="header"><label>octoprint</label></div>
             <div id="send-to-octoprint" class="f-col box">
diff --git a/web/kiri/lang/en.js b/web/kiri/lang/en.js
index 9ca5b021..23a15808 100644
--- a/web/kiri/lang/en.js
+++ b/web/kiri/lang/en.js
@@ -521,6 +521,8 @@ self.kiri.lang['en-us'] = {
 
     // CNC OUTLINE
     co_menu:        "outline",
+    co_merg_s:      "merge overlap",
+    co_merg_l:      ["merge overlapping lines to prevent overcutting into adjacent solids"],
     co_dogb_s:      "dogbones",
     co_dogb_l:      ["insert dogbone cuts","into inside corners"],
     co_dogr_s:      "reverse bones",