The lower seems to be covered, how about building an upper stand into the tray to go next to the lower stand?
Make the base/tray wider and put two posts on there with retaining pins that you could just put the upper on using the pivot/takedown pin holes. Have the upper posts higher so you're no ducking down to see in the barrel. Position the so that the weigh of the upper doesn't throw of the balance.
Maybe throw in a form tray in the shape of the bolt parts so you don't lose track of them... looks like they might get lost in that dark black tray if they were just rolling around loose... and a raised "nipple" to place the bolt carrier on for scrubbing carbon out?
Non-slide/skid rubber on bottom so it doesn't slip around on a flat/slick table top?
Would be sweet for cleaning... nothing would touch the deck using this.
Is the plastic resistant to solvents and such?
Plan on selling them in the EE, getting an Industry partner membership, or selling them on eBay? Or all of the above?
Anywho... my $0.02 after tax, tags, tips, s&h.