I put together the chassis - I marked the screws 1cm from each corner and roughly the hinges, all clamped for drilling (very high class setup, I know 
):
[SPOILER="clamped"][MEDIA=googledrive]1UkWqHUu-gcNOqO3BFqWy4OhnhHRTmTxU[/MEDIA][/SPOILER]
There was quite a bit of flex on the longer edge of the bottom box, I updated the design and moved two of the standoffs from left-right to top-bottom (added them after I took the photos).
Doesn't actually look that bad, but I'll definitely have to find other hinges - these look horrible. They were the cheapest ones I could get in reasonable time for the prototype, though (my hand on the second photo for scale). The bobbin mounts made quite good legs. Conical, or with rubber at the bottom would have been better, but I couldn't find any in M4 size so these will do.
[SPOILER="prototype"][MEDIA=googledrive]1V7L2z7dSqLqMfSpMgy7wpK0jN1lRPRZ-[/MEDIA]
[MEDIA=googledrive]1V5JS8RkbjFcsjF3MVmJFEQ1E-h2fh8LM[/MEDIA]
[MEDIA=googledrive]1VL31Sql9lB1EAXBGw5JSos5gKDHS2Wub[/MEDIA][/SPOILER]
All in all, I'm quite pleased, not too bad actually. I'm waiting for the nylon threaded studding - cut to around 35mm will connect both plates and let me adjust the height:
[SPOILER="back box prototype"][MEDIA=googledrive]1VFS-8IdkcSQaRUz0ujiqTo32t8l0tyuh[/MEDIA][/SPOILER]
