Where to get 3D files for LEGO bricks? I am constantly in search for a particular rare brick from the 1990's which is ridiculously expensive on BrickLink and also hard to get. So I am thinking about printing it on a 3D printer to be able to finish projects. I understand, a blasphemous behaviour. Please let me know where to get the needed 3D file.
The canonical location for 3D models of LEGO bricks would be LDraw, with its huge catalogue of official parts.

Another resource specifically catered to the 3D printing community is PrintABrick. Their library is not as big as LDraw's, but they offer ready-to-print STL files.