I'm trying to inset and extrude a peripheral slot as shown on this cube:


Except I'm trying to do it on a rectangular cuboid which has one side/face split into multiple non-planar sub-faces:

cuboid with non-planar sub-faces

Method I used on the cube was to enter the edit mode, create two loop cuts for vertical slot in the middle, then select the outer edges of the front face and inset them. Finally, I selected the faces I wanted to be extruded and I extruded them in the direction I wanted (inwards).

Now, I have two issues when I try to do the same on the cuboid:

  1. The inset of the outer edge is not uniform, i.e. side insets are bigger compared to the top and bottom one. I would like them all to be the same width. Is there is a setting to make this inset an exact value instead of being proportional?

  2. I have no idea how to loop cut the vertical slot in the cuboid - loop cuts are aligning with the slanted edges. Any idea how to cut vertically across multiple sub-faces?

I'd appreciate any advice. Thanks.

  • $\begingroup$ Hello :). Inset has an 'Offset Even' checkbox. And for the middle loopcut you can use Knife project if you want a perfectly vertical line. $\endgroup$ Commented Feb 5, 2021 at 20:27

1 Answer 1


Something along these lines might do it.. just following my nose, someone might find a snappier way..

The inset of the outer edge is not uniform

I think the only reason for this is that you scaled your cube in Object Mode, and it's carrying an object-level non-uniform scale. CtrlA > Apply the scale of your object, and if your inset is set to even, it should be even.

I have no idea how to loop cut the vertical slot

It's not a loop-cut, because it's not a loop. K Knife, with C to constrain its direction orthogonal to your view, should do that. Cut from an orthographic front view. The only problem is, how to get the cut right in the middle..

enter image description here

  • I EZ extruded the top edge up in Z..

  • CtrlX Dissolved the odd vertices, and Edge menu > Subdivided the top edge once to give me a guide-point in the middle. Then, looking from the front, You can K with C to constrain, cut an edge straight down the middle of the front region. You can discard the guide-edge once you're done with it.

  • Then, as you have before, you can I inset the whole front region twice, remembering or CtrlC copying the second distance, the width of your rebate. Now select the central cut line and CtrlB Bevel it by half that distance. (You can paste in the copied Insert distance and add a /2 after it into the width field of the Bevel's adjust-last-operation panel)

  • Then E extrude as before, for even, centered rebates:

enter image description here

  • You can SY (or whatever dimension) 0 with the Pivot set to Median, to flatten the backs of your grooves.
  • $\begingroup$ I don't have enough reputation to comment so please forgive me for replying by writing an answer. I just wanted to say thank you Robin Betts and Jachym Michal. It seems that Offset Even was on, however resetting the scale did the trick. I do appreciate the rest of your workflow as well Robin, it's really helpful to gain insight into step-by-step thought process when modelling. $\endgroup$
    – mk1138
    Commented Feb 6, 2021 at 1:32

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