Designed to work with REV robotics components.
Core Hex Motor
3x8mm hex bolts
3x16mm hex bolts
3mm Nylok nuts
15mm extrusion
GT2 6mm belt (commonly used in 3d printing)
6mm idlers
Zip ties
You can use a simple extension spring inline with the belt to keep constant tension.
The author hasn't provided the model origin yet.