This is an old revision of the document!
I'd been working on a device to photograph slides to convert them to digital form, and was about 75% done with it. I still had to finish the part that would hold the slides and light them from the rear. I had prototypes, but wanted to laser-cut the final working version.
I've abandoned it all, because I saw this: http://metrixcreatespace.com/post/20108216677/diy-slide-scanner-lets-say-you-have-a-large
So that's the direction I'm headed in now.