Being slightly low on cash... I think I'll try and make an imitation... 
Me too, but in 5x7" (cos I've got the filmholders)
A sneaky peek (I'm refining the design of the back- want to make it interchangeable so I can use it in future to go on a camera with a lens and stuff) of my scheming:
I'm currently sitting with two darkslide on the table beside me, which I have been measuring up to do something similar.
Like the look of your plans. Have you got as far as deciding what materials to use etc.
No doubt Francois will miss the plan stage and go straight to the camera phase itself.
Combine these with the recent how to make a pinhole thread and we could have some fun.
Mike
Yeah, I'm sure Francois will do something super cool (no pressure F)
I'm gonna use aluminium angle for most of it, with some ply or mdf for spacers. The lens cone will be 'stitch and glue' thin plywood. I think I'll use shockcord to spring the back. When I get the design finalised and build one to see if it works I'll make the design files freely available. My intention design a graflok compatible back that anyone with a saw, a drill, a measuring tape and opposable thumbs can build in an afternoon. I'll scale the design for 5x4" and 8x10" too...
Will build it over xmas when I've got some time off and then try making some cyanotypes (I've got pent-up creativity from the last few months of being exclusively sciencey). Only problem is my darkslides are not 5x7" as I thought but 13x18cm- struggling to find some 13x18 film in the UK.
(sorry, well OT)
