Here is a perimeter marble run around my sons room. The track runs around the entire room near the ceiling. The supports are walnut and a majority of the tracks and other parts are birch. Gear motors are run by "AA" battery packs. The marbles are 1 inch diameter. Go to the following link for more information on the building of this track: www instructables com/id/Kinetic-Marble-Track-Ar
![Perimeter Marble Run RBS](https://cdn-ak-scissors.b.st-hatena.com/image/square/818dc24a383898c1be94b611fe721f09aa42ea94/height=288;version=1;width=512/https%3A%2F%2Fi.ytimg.com%2Fvi%2FRTxmTTisThY%2Fhqdefault.jpg)