Neat idea. I think I'll build one in the barn and be ready to put it in after ice out. You could use plastic cable ties to attach the lattice, they come in all sizes, and I think 4" PVC would be more than enough to keep it floating.
Scrap plywood for the top might make a place for minnows to spawn similar to floating pallets.
Use the cable ties on the 4 corners and place it on a flat spot where it would rest on the bottom of the pond so the larger predators wouldn't get inside from the bottom.
Being all plastic (other than the plywood)it should last quite a long time and be easy to pull out and hose or power wash off any algea or crud that attaches, maybe once a year.

Dan

Mistakes are proof that you are trying.


Dan