Mesh cage divider-- ideas?

Technically this is for a rodent build, but you guys are the masters of cage building, so I thought I might fish around for some ideas.

I'm looking to build a divided cage (or just the divider itself) for separating and introducing breeders gradually without the cage-in-a-cage method. It needs to allow for free air-flow between the sections but must be fairly rigid, flush to the edges to prevent mingling, and, most importantly, chew-proof.

I've had a few thoughts on how I might do it, but perhaps someone will have a simpler or better idea. I use both free-standing bins and standard glass aquariums, so either will work.

The rodents in question are campbells dwarf hamsters and they are not feeders. Any suggestions are appreciated