I moved the sketches for the loft so they won’t intersect the main box. And it works that ways. It’s strange, and I’m not sure it’s the real reason it failed before.

Thanks, I verified the sketches twice, there’s no open wire. Fun fact, if I delete all the other objects, Freecad can happily make the loft…

thanks, I’ll try that. so far I only used the Part Design and Sketecher workbenches, I’ll try the Draft.

3D printing, I plan on placing the left angled side (of the top left sketch) on the printing bed, this way I should avoid supports.