I finished up two home made track cleaning cars. The design is simple, a 1x2 for the frame, added trucks and couplers, then a cork cleaning pad glued onto a old car weight. The pad slides across the rails, giving them a good wipe. The pad is held in place by two nails, glued to the top of the weight. I added three nuts to give the car more weight.

I used three of these cars. I push one ahead of a loco, then a second car with Liquid Wrench on the pad, then a third car trailing with a dry cork pad. Works great and keeps things running fine.