UHMW - ulta high molecular weight, 4'x 8'x 25", average cost $200 a sheet. <BR> <BR>HDPE - high density polyethylene, 4'x 8'x .25", average cost $100 a sheet. <BR> <BR>Does the sliding surface of a fun box have to be UHMWP, or would HDPE work as well?

Is that what they really use on sliders?? I would think both of those are too soft.

hdpe is what i've seen used the most. you'll want 1/2 in. thick though.

it seems that with boxes you are really limited on your tricks in wakeboarding.

Either will work you need to take a look at the UV rating on both. I believe that HDPE does not have one. That will be key if your planning on having it for a while.