Thanks for the sketch. Could you email me the .skp file to email@example.com? Actually, I bet if you email it to Denise as well she'd be happy to put it on the Light Farm website.
My local plastics house has 1" thick acrylic (as well as the 1/2" like you used here). For your Rev. 2 coating blade, are you planning on simply extending the dimensions upward 1/2"?
You said "plexi" - is that the acrylic version of "plexi" or the polycarbonate (actually real) "plexi"? I can easily get acrylic at 1" but polycarbonate only up to 1/2".
Did you think of HDPE? Or VHMW or even UHMW Polyethylene - it's supposed to be similar in many properties to Teflon - low coefficient of friction, chemically resisitant, resisitant to abrasion. And can get them all cheaper locally than the acrylic stock.