Hi David, also there is one other problem in your original curve - there is a small region of the curve that has a tiny "curly-cue" self-intersection spot in it:





So notice there after zooming in that there is a little odd piece that sticks out extra? That's not good.

Basically any messy areas in your original curve like this will then become messy areas in the solids which will then be difficult for the intersection algorithms to resolve.

- Michael

Hi David, I've attached here a fixed up version for you - I flattened your original curve, and also delete 2 control points that were making that self-intersection happen (the curve was kind of running back directly on top of itself in those spots), and then did a new extrusion from that. Now it should boolean for you ok.

- Michael

Too speedy for me, MG!!!

Thank you guys!

Finally the mistake was me. I´m still a clumsy modeller :-(

Thank you for the explanation and the fixed curve

"Finally the mistake was me. I´m still a clumsy modeller"

Yes, I've learned that lesson myself LOL

I'm now very careful about where I put my lines! :D

I find that generally when there's a problem like this, I just need to inspect (or recreate) the affected parts of my model, and it works properly.