Yes, you are right the plastic bricks are injection-molded. Sorry for not being clear, but I was actually thinking about Mindstorms + TETRIX, which includes precision milled metal parts; http://www.legoeducation.us/eng/categories/products/universi... . There was an and over here that got deleted during editing. Lego's tolerances are crazy, btw. In some cases it's as low as .04 mm.