Gooberz@Kingcactuz You're going to want to pick up "608" bearings. The ones I use with good results are Spitfire Cheapshots, available at most local skate shops. You may need to lightly sand the inside of the spinner holes.
Gooberz@fb1d382 If you're having issues with the bearings fitting, lightly sand the print. Depending on the tolerances of your bearings, you may have an easier or harder time getting them to fit.
Gooberz@fbf16cc That depends on what type of plastic you order. Shapeways offers tons of stuff, from PLA to metal casts.