Ive always loved grip training. I have all the grippers and got up to closing a number 3 CoC. (Captains of Crush). (Just with my right).
Thick bar or thick-bell training as well. I have a "baby Inch" Thomas Inch bell. Took a while but I got it with both hands.
I have a wrist-roller setup (Where it doesnt need to be held up by the person) so it saves delt fatigue to just focus on the grip/roller.
I have some other gadgets as well (Axle bars, pinch grip blocks, rolling-thunder handle, etc).
Lots of fun and a break from normal PL or BB type training...