Make 4 caps for the winding drums. These caps will fit in the ends of the cardboard tube and 2 of them have a D-shaped cutout in the center so you can connect the d-shaft of the dc motor. The other two caps are connected to a free-spinning axis and bushing.
On our file, a cap is composed of two parts. The part with tooth (part2) goes into the paper tube and should fit very tightly. The other part (with holes, labeled as part1) is supposed to be glued to the toothed part and goes around the edge of the paper pipe, guiding the scroll. Many of us don’t have a laser cutter at home, so in this case, you may consider using motorMates. Tips & tricks for using the motorMate can be found here -- http://littlebits.cc/fridays-tips-and-tricks-motormate