The plastic end caps on my woodworking roller supports crumbled. These printed replacement parts support the ball bearing and fit snugly in the two inch sleeve.Conveniently, this roller assembly also fits nicely in the 1Kg ABS spools currently shipping from Makerbot.After printing two end caps, press the original ball bearing assemblies into the inside of the cap. With a 15% fill, the side walls have enough give to firmly retain the ball bearings.Slide the end caps into the main sleeve. Use some tape to increase the snugness if necessary.