I just had an idea that was awesome.
Instead of using basswood, or Baltic Burch plywood, I could use cardboard.
But not your everyday, lame corrugated cardboard.
I'm talking about that reinforced, multi-ply "plywood" cardboard.
Here's NighthawkInLight on YouTube with a longish video explaining how to make and use cardboard for furniture, etc.:
https://www.youtube.com/watch?v=45JhacvmXV8
We can market as "eco" and "recycled". And it doesn't even really need to be waterproof! This is great!
The only catch that I can see right now would possibly be thickness and having to adjust the slot sizes. Wheat paste is the adhesive. Can add white glue.