Hey, these ideas are great and got me thinking more, along with am coffee...
Would the wax repell collodian? If so, they, ie wet plates, could be used in metal book form dry plate holders and the front edges wouldn't get messed up.
An old window frame could be used to hold onto glass while tipping and pouring; a hole, cork, and spout in a corner would let out excess material; waxed edges would keep it all clean. The frame would have to be the same size as the camera.
Well, why not make a window frame camera? Corners often get loose so it could be taken apart and grooves cut for a dark slide. Lots of windows are trashed around here when new ones are installed. I've used them for silk screen printing. Also, I've sand blasted glass in a stone shop as well as handled hydrofloric acid which eats glass to frost it, so that is possible to do as long as a shop is nearby making granite memorials. Bathtub refinishing companies also use that acid.
Glass could be silk screened and if warmed any texture would smooth out; that's a guess, screens can be huge, not as large as for a cascade trough but large enough to cut up glass after coating. Anyway, if large enough, texture would not matter from the diagonal viewing distance.