Hardest part of the slide scanner...

I knew I would get to this point. This is the hardest part of the slide scanner as I see it. What you have up there is part of the mechanism that'll hold the slide flat against the platen so I can take a photograph of it. The problem that I'm solving for here is that slides can be different thicknesses and I'll need to allow for around 0.05" of tolerance (maybe a scosh more as well) to account for differences. The "normal" slides are 0.05". Glass mounted are 0.10".

How to take up the slack?

Springs.

So I need to engineer in enough rigidity into this along with having nested sliding joints. Oh, and it has to be printable as well.

Maddening, I tell ya.

After this, I'll have another stage that looks like this, but with way less critical constraints to taking a picture of the slide mount itself.

But it's getting closer!  :-)