Dear Chimera developers, Chimera has the great feature of STL export, very useful for 3D printing models for research and teaching. May I make two suggestion to improve this feature even further. 1 - Remove invisible internal and therefore unnecessary structures. Chimera generates a lot of internal structures that complicate printing and are pointless for STLs. This includes inside surfaces at the end of ribbon cartoons (red below). [image: Inline images 1] as well as copious amounts of invisible internal surfaces for wire and ball and stick models. [image: Inline images 2] If these were automatically removed, STLs would not only be much smaller but also much easier to print without remashing. 2 - Reduce the number of vertices for atom models. Ribbon conversion to vertices is already good, but as can bee seen above atom models are converted using far too many vertices inflating the resulting STL files. I'm aware that this has been discussed and listed previously as a bug but the problem remains and makes for difficult to use STLs and bad 3D prints. Best regards, Jakob Suckale, PhD Lecturer in Biochemistry University of Tübingen +49-7071-29-73363
