Pinch Blocks, Farmers Walk Implements , etc.
This is a pair of what i call the light weight farmers walk implements. They are good for around 300lbs. each. Heavier ones can be built for around 600lbs. each. Overall length is 60 inches. These here will run $100.00 plus UPS shipping, heavier ones will be $150.00 plus shipping
These wrist rollers can be made from PVC pipe or steel pipe in various sizes including 3 inch.

Below are pinch blocks. These happen to be made out of aluminum. I normally use steel. These are a great tool for pinch grip strength increases and can be made in various sizes.  The cost on these is $11.00 plus shipping. Just add a plate loader and a carabiner and you are ready to train.
The softball gripper is a unique tool.