About this 3D model

These marble rollers are meant to be used as a learning demonstration for acceleration due to gravity. There are 4 individual tracks, each with a specific profile. 20 degrees linear track, 30 degrees linear track, 30 degrees constantly curving, and 60 degrees constantly curving. The tracks are each between 5 to 10 grams. Meaning printing cost is approximately 10 to 25 cents per track.