My kids and I at Give Me A Chance in Ogden Utah built a classroom gyroscope from Maker Pipe. Rather than mess with wrist or pin bearings, I just slipped a 1/2 conduit inside two 3/4 inch conduits. You can see it in a video at the GMAC website: http://www.givemeachanceutah.org/building-a-gyroscope-in-the-classroom/