diff --git a/src/kiri/core/conf.js b/src/kiri/core/conf.js
index a6c09d08..2e9aa772 100644
--- a/src/kiri/core/conf.js
+++ b/src/kiri/core/conf.js
@@ -441,6 +441,7 @@ export const conf = {
                 camRoughTop: true,
                 camRoughIn: true,
                 camRoughOn: true,
+                camRoughOmitThru: false,
                 camRoughOmitVoid: false,
                 camOutlineTool: 1000,
                 camOutlineSpindle: 1000,
diff --git a/src/kiri/mode/cam/cl-ops.js b/src/kiri/mode/cam/cl-ops.js
index 90dff2a4..944f8d2e 100644
--- a/src/kiri/mode/cam/cl-ops.js
+++ b/src/kiri/mode/cam/cl-ops.js
@@ -227,6 +227,7 @@ export function createPopOps() {
         voids: 'camRoughVoid',
         flats: 'camRoughFlat',
         inside: 'camRoughIn',
+        omitthru: 'camRoughOmitThru',
         ov_topz: 0,
         ov_botz: 0,
         ov_conv: '~camConventional',
@@ -246,6 +247,7 @@ export function createPopOps() {
         voids: UC.newBoolean(LANG.cr_clrp_s, undefined, { title: LANG.cr_clrp_l }),
         flats: UC.newBoolean(LANG.cr_clrf_s, undefined, { title: LANG.cr_clrf_l }),
         inside: UC.newBoolean(LANG.cr_olin_s, undefined, { title: LANG.cr_olin_l }),
+        omitthru: UC.newBoolean(LANG.co_omit_s, undefined, { title: LANG.co_omit_l }),
         sep: UC.newBlank({ class: "pop-sep" }),
         exp: UC.newExpand("overrides"),
         ov_topz: UC.newInput(LANG.ou_ztop_s, { title: LANG.ou_ztop_l, convert: UC.toFloat, units: true }),
diff --git a/src/kiri/mode/cam/op-rough.js b/src/kiri/mode/cam/op-rough.js
index 06e2630e..7145bb73 100644
--- a/src/kiri/mode/cam/op-rough.js
+++ b/src/kiri/mode/cam/op-rough.js
@@ -144,6 +144,7 @@ class OpRough extends CamOp {
 
         // inset or eliminate thru holes from shadow
         shadow = POLY.flatten(shadow.clone(true), [], true);
+        if (!op.omitthru)
         thruHoles.forEach(hole => {
             shadow = shadow.map(p => {
                 if (p.isEquivalent(hole)) {