Just cut a piece of plexi and drill some holes and you're good. The knobs and switch are likely gain and crossover and you should be able to work them out by just fiddling with them a little trial and error. A 20$ amp (if it works) is not bad.... hell it's probably 10$ worth of aluminum melt value in the heatsink.
Is TREO still around? Pretty sure they just used off-the-shelf Zenon boards so it's probably the same board as a dozen other amps produced in the same time period.