These screw-on easily using regular drywall screws. Create your own modular hangboard.

Hang them for a protonating workout.

Flip them upside down - there are holds in both directions. Girth hitch the two-finger pocket and it works upside down as a ring as well.

Screw them on plywood as part of a modular hangboard.

The lower screws placed 1/2 inch above the bottom of the board enables your fingers to wrap all the way around on the finger pocket - ring hold. See figure to right.

Screw-on. Four edges. Flip upside down for more sloping edges.

Screw on plywood. Increasingly larger two finger pockets with a nice ball hold on top. The balls also form a series of pinches.