Hi Mike, basically booleans already have projection built into them, so if you want to do a boolean you can do it directly with the original unprojected 2D curve. Inside the boolean command that 2D curve will get extruded into a solid and then that solid will be what's booleaned.

When you have a projected curve, that won't work for a boolean anymore since a curve that's bending around in 3D space doesn't have a really well defined extrusion direction anymore unlike a 2D curve has with its plane normal.

It is possible to use a projected curve in other ways though, like you can use it as a path for sweeps and also you can use it as a cutting object in the Edit > Trim command which works at a surface level instead of at a solid level. Trim also has projection built into it as well though so you can use it directly with the 2D curve as well instead of doing a separate projection step.

If you have more questions about the projection or how to do the boolean could you please post your 3DM model file with your objects in it? That would help to give you more specific advice.

- Michael

Excellent explanation as usual, especially the comment about the lack of well defined direction. Let me play around with my model based on your advise and I'll try to comment about my progress! Thank you again.

Process here: project curve onto box / use projected curve to rebuild label object curves then add surfaces.

Hi Mike, also instead of using project + rebuild for a case like that you could also use Edit > Trim on your box with the 2D curve as the cutting object. That will do a projection automatically in the Trim, you don't have to do it as a separate step.

- Michael

My objective is to create a label on an object without cutting, trimming the base surface. Trim does help but it's trimming the surface which I don't want. Make sense?

Hi Mike, do you mean you want your "label" part to be a second surface that has overlapping surface area with your main one? If so you can still use Trim to do that, just use Trim to produce the label, select the label and use Ctrl+C to copy it to the clipboard, then undo the Trim so you go back to your original surface and then use Ctrl+V to paste in the trimmed one.

But it can be problematic later on to have surfaces that have coincident surface areas like that. The other way you could do it with Trim is to not select any pieces to discard in the Trim, just right-click at that stage of the Trim command and it will leave all the cut up pieces behind rather than removing any pieces.

If that doesn't make sense then maybe I'm not understanding what you're trying to do, could you please post your 3DM model file in that case?

- Michael

No you got it. You are amazing at deciphering my message. I will check that out!

That worked.

perfect solution.