OK, had to look at the pictures twice, the inside box is just a holder for the weights with the bottom cross to push the follower in the mold, and the outside box is sturdy guide for the inner box.
! Looks sturdier than the more common 4 corner dowel guides that some people build, less chance of weights toppling over. If you decide to go for different sized hoops, then you can just chang out the bottom parts.
Question, what happens to the whey, will you have drain tray or just raise the white board above the "puddle"?