Personal piece, 10.25 x 14.25 inches, oil on plexiglass, 2012. Also, I tend to receive many questions about working on plexiglass when I post those pieces, so:
I prime the plexiglass with two coats of acrylic gesso applied moderately heavy with a pallet knife. I don't generally sand. Once gessoed, the surface is opaque and not meant to be viewed backlit. The texture is similar to working on wood panels (primed the same way) but a little bit slicker. I first used plexi as a surface simply because I had some handy and thought I'd try it for studies. The feel was pretty good and, along with the fact that it is light weight, does not warp, and is thin but durable (so easy to store), I still will use it whenever I happen to have some laying around.