I started drawing out some ideas of how to trap the lens in a frame and came up with a couple ideas.

I jumped into modelling a pair using a leaf spring like retaining mechanism since one of the tricky aspects of this project will be allowing for variations in lens thickness.

An exploded view

Not bad for a first draft.

I also came up with a bent wire arm design where a single piece of wire fits into guide channels and then enclosed in the hinge mechanism to hold the assembly together. This would allow for easy sizing changes so I'm pretty keen on this. I will definitely have to go back later with real wire dimensions and such, so what I'm showing is pretty accurate, but still just an approximation. Hopefully it makes sense. The rotational post is off-center to allow for the folding action to be one way. I think the support (clamping structure?) is too complex and frankly.... too big. Even though it is rather small. Guess I'll have to see how it fits with a frame or integrate the supports into the frame itself.

For reference; the channel block as shown is 1mm tall, wire is .1mm diameter.