Wrist Roller Grip Training Tool

Wrist roller is a grip training tool intended to train pinch grip on a handle that wants to rotate out of your hand.

To complete the tool add some rope (I used ~1m of paracord). Thread both ends of the rope from the same side each through separate holes, making a knot or two on the other side.

Then clip a carabiner onto the rope and attach some weight to it.

To use the tool, wind up the rope around the tool (both strands from the same side, as pictured in picture 2) and grip it in your hand in such a way that the rotation caused by weights would try to open up your hand - it should rotate into your fingers and away from your palm.
Your goal is to lift the weight without letting the tool rotate.