I don’t often blog promotional giveaways, but this one is pretty sweet: Minnesota’s Proto Labs offers injection molding in a bunch of different plastics. The really cool part is, if you’re in North America and you register at their site, they’ll send you a free 4x4x4 unit polycube puzzle, with nine pieces, each molded in a different color and from a different polymer resin. There’s green HDPE, white polypropylene, mauve ABS, clear polycarbonate, yellow polycarbonate/ABS blend, orange polyoxymethylene, red polyester, blue nylon, and black glass-filled nylon. And purple horseshoes! I already snagged mine!