I'm going to be printing a prop gun in two halves and in order to glue it together perfectly, i want to print an outline mold of the gun so both halves can set straight.

I tried using the knife project tool but it doesn't cut the outline of the gun.

This is what using the tool normally is like: It only cuts the trigger guard portion.

And this is what i would like to do: I would like to cut only the outside of the of the mesh model onto the plane in the back, is there any way to accomplish this?

I can upload the file of the half gun if requested.

Here is the finished product, thank you:

  • $\begingroup$ I'm sure you must have taken this into account...If your model has undercuts , the seam in the plane X=0 may be smaller than the silhouette. So your guide mold would have to be shallow enough for the projecting parts to lie outside it, or the mold enlarged in those areas to accommodate. $\endgroup$
    – Robin Betts
    Commented Apr 12, 2018 at 8:50

1 Answer 1


I assume that the half-gun has a flat face on the side it's cut.

You can extrude that face out so that it goes through the plane and then subtract the gun from the plane.

Here's an example with a half-suzanne. With a bit of imagination, it looks a bit like a gun :-)

Process of cutting an object shaped hole in a plane

And here's the final result

Result of the above operation

  • $\begingroup$ This worked perfectly. With a little fiddling around tinkering I got exactly what I wanted, thank you. oops idk how to add a pic here to show but it looks great $\endgroup$
    – Shik
    Commented Apr 12, 2018 at 8:28

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