DIY wooden marble runs
A UGEARS marble run is a mechanical wooden model kit: you press the parts out of laser-cut plywood boards, slot them together without glue and drive the finished run by hand. The chain-lift marble run, for example, has 400 parts and takes about 7 hours to build.
The difference from a single marble track lies in the kit itself: the runs are designed as a system. Connectors are included, and several runs become one layout — driven by a single crank.