After a good deal of bug-fixing, optimizing, and recoding, I am release Beta 4 of Brix Builder, the first true 3D perspective hidden-line rendering engine ever written in TI-BASIC. Betas 2 and 3 were private, unreleased betas, but Beta 4 is a semiprivate beta available to all Cemetech members. Please take a few minutes to download it and try it; while there is not yet a readme, the controls are fairly intuitive. Post questions, comments, and bug reports on the forum. One of the things I am considering for the final release is adding an optional shading engine, which would be yet another TI-BASIC first.