The first prototype of the SP-2810 should arrive next week. It's a monster: over 12" high and 14" long and holds almost two liters of solution. It will accept two film holders, allowing you to process two sheets of 8x10 film at a time. (Click on the above image to download the full size rendering.)
The design is symmetric: either port can be used as a fill/drain. Or use them both at the same time, if you're that coordinated. (Here's a more detailed pdf: Cut away drawing)
One of the challenges we faced was designing a film holder that was easy to load and yet would still grip an 8x10 sheet of film during inversion (it gets pretty violent inside the tank). We ended up with a hinged frame. You'll place the film holder on the bench and open it like a book, lay the sheet of film in place, close the top of the frame and snap it around the film. Haven't actually tried it yet, but we're optimistic.
Questions we're pretty sure you're going to ask:
1. Why only two sheets of 8x10; can't you fit two back-to-back?
Maybe. Right now we don't know how well the film holders will work. We also wanted to accommodate double sided X-ray film and are concerned with chemical flow to the back side of the sheet in a dual holder (the sheets will be pretty close together.) Once we see how well the single sided holders work, we can reconsider a dual version.
2. What about 5x7?
Probably. We actually stretched the tank a bit to accommodate the extra length needed for a 5x7 holder (two sheets, side-by-side; two holders will allow for four sheets per tank.)
3. How soon?
If the testing goes well, we'll be launching a Kickstarter next month.
4. How much?
The Kickstarter funding level will probably be in the $100 range; production units will be higher, we're estimating around $150.
Remember, this is just our first prototype (the SP-445 went through eight, but we've learned a thing or two). The design will change; constructive feedback appreciated.