How can I subtract these two shapes?



Hi, I am trying to make a small crown shaped playing piece for a game.

I have constructed a cylinder, and a shape that is 4 triangular prisms joined together that I hope to use to cut away the spiky top edges of the crown.

I can’t seem to use the subtract tool because it complains about not being a solid.

I thought maybe the issue might be that I have not properly combined the triangular prisms, I tried Union but had similar issues with a warning message. I’ve tried cutting away internal lines but it quickly gets very messy and unmanageable.

Can anyone help, or suggest a better approach?

crown cutter.skp (1.3 MB)


First, you have to make crown cutter as a solid.
(You can make crown cutter with 4 prisum shape solid group using solid outer shell command.)

Then you can cut cylinder with crown cutter using solid command.

crown cutter.skp (1.4 MB)


You might find the Solid Inspect2 plugin* by ThomThom helpful - it can automatically fix some problems that make a component or group not solid, like internal faces, stray edges, or nesting of components or groups (by exploding them, which might not be what you want!).

And other problems it can’t fix automatically are identified for you.

  • From the Extension Warehouse or SketchUcation plugin store.