When I started out teaching fitness and training people in a double garage in Worthing, West Sussex (CrossFit West Sussex) the plylometric boxes that we commonly use simply weren’t available so these boxes had to be made.
Commonly, the plyo boxes now available are 20/24/30 which is a big jump for most people, especially people getting back into fitness.
My solution to this, both back as one of the UK’s first CrossFit affiliates and now as a (currently) garage gym, is to build custom size boxes.
This is a 12 inch high box, but 20/24 inches in its width. It’s a great starting point whether learning to do a bodyweight squat with the box behind you to squat onto, box step ups or jumps.