Hi Metin, glad you're enjoying the new beta!

> One minor remark: if you use extrude on the cap of a cylinder solid, it leaves
> an edge loop when extruding outward. Is there a reason for that?

It's because currently the geometry library only knows how to merge faces together during booleans when the 2 adjacent faces are planar surfaces that are coplanar, or also when the 2 surfaces were trimmed and share the same original underlying surface. 2 cylinder pieces that are adjacent to one another do not fall into either of those categories and so do not currently get merged. But in the future I do want to try and update the face merging process to work in that case.

- Michael