Boilie Roller 20mm (RollBall)

This is boilie roller for Ø25mm balls.

You need two ball-bearings (outside diameter 80mm / inner dia. 40mm / Width 18mm) //for example: SKF 6208 or anything cheeper 
2x M8 nut, 6x M3 nut, 6x M3x18 DIN 912 screw, 1x threaded rod M8x~300mm

cylinder is from two parts for printer fit 
for better assembly print 4x pin Ø10 (in print files)

For drive you can simple use cordless drill. :)