Jump Box Sources

Looking to get some vertical jump boxes, similar to what DeFranco uses - can anyone point in the dirction of a source, or give me some more info on their construction (ie. dims) so i can get some made?

I just had mine built by a carpenter I know. They are made out of plywood, so they’re heavy, but they can stack on top of each other or inside for storage and cost me $150 for a full set (12", 16", 20", 24", 30", 36") that costs like $600 when you buy them from some other places.

Sweet. Thats exactly what i need to know. Thanks.