Having grown tired of modified film holders, I've been wanting to build my own dedicated plate holder for collodion work for some time, but after failing miserably at 2 previous woodworking attempts, I decided to go the Acrylic route after seeing several made in a similar fashion. My goal was to make one that could be used with any 8x10 camera without having to modify the camera back to accept the holder.
After cannibalizing several old wooden holders, I came up with a basic design as well as the T distance to get the plate equal with the placement of the ground glass, I went about layering the acrylic so that I would have a shelf set at that distance that the plate could rest upon and then built upon that. It took a few weeks and a couple failures, but I finally got it. The result was a successful, light tight prototype that I've been continuing to improve on until I came up with my current design that has gone out to a few folks to test. So far, so good. I've been loving my original prototype and have run many plates through it without problems.
Nothing like DIY!!! (Especially when there aren't many other options)