Thanks for all of the responses!
I did 13/16" T-Molding on my 3/4 upright cab, and that took more time than I would've liked, hence the pre-finished route. I'm more interested in the design of this next build over all of the manual labor required
. That said, if I can't find 1/2 (or even up to 5/8), then I'm going to go ahead and do as you suggested leapinlew.
Lilshawn, I'm not too worried about screws to hold the thing together as I plan to route out shallow (1/16" or so) areas on the cab's inside to glue square dowels to hold the various pieces square and together - on top of glue & routing at the joints themselves. True statement though about the screws. The only place I can think of needing them is the CP -- where else did you screw things in on your builds?
I made some more calls today, and for those in the area, it turns out that Woodcraft in Rockville has 3/4" melamine in black or white. I was told to give A&M Supply a call from the Woodcraft in Alexandria to see if they could order it -- I'll try that on Tuesday.