The Wrist Trainer is a tool used to reinforce your wrist for climbers. It allows you to do flexion, extension, pronation and supination exercises. This model is inspired by the work of Hooper's Beta and its product, the Torque Pro. Check out his website & YouTube for tips and tricks.

For my tests, I've printed using PLA and it's holding up pretty well for now. I'll change the type of plastic when it breaks. I've used 5 walls and support only on the print bed. To finish the assembly, you should buy three carabiners and one metre of rope. I've used a nylon rope with a diameter of 6 mm. 

 Also, you can find another model on the web by Nicholas Jacob.