(Note: This is for after the big updates)
As a builder, I like to use the CSG engine. It's quite handy after all, unless it fails. When I try to union something that is 2D (Meaning it has a mesh inside and one of the axis on Scale is 0), it brutally fails, even on a simple wedge. You may wonder "Why are you unioning 2D items"? Well, I also am a 3D modeler! I don't appreciate ROBLOX breaking user-meshes, so I am openly stating I want a loophole so I can AT LEAST not get 10 FPS when I have 5K parts in a 2x5x2 stud area. By the way, clearly I'm not saying "Add user meshes!", but instead saying "Consider improving the CSG engine after the big updates so that I can remove lag on meshes that I may use that are not part of ROBLOX", despite getting close to the big, bad topic.
Also, would any moderator care to share why user-meshes were purposely broken ( http://wiki.roblox.com/index.php?title=Anim8tor_exporter_script )? With user-audio, it's quite interesting how ROBLOX would decline something just as able-to-be-affected by copyright or inappropriate content. The question has been bothering me for quite some time.
Hm.
In the mean-time, I suppose I could work on a "Union region" system that removes clipping from geometry (Two pieces inside of eachother) because I've noted how that seems to be where a lot of the problems are.