I'm trying to figure out what this stuff is called. Home Depot employees don't have a full brain to share between them.
It's super thin, probably around 1/8" but not thicker than around 1/4" or so. Recently I've seen it on that crummy IKEA furniture as "filler" panels in between the frameworks. The pegboard everyone hangs in their shop is right around in that same ball park, just without the holes. I don't care about veneer or melamine if I can get it cheaper without.
In recent times it's composed of a something between pressed wood and paper fibers. In the "old" days, I've seen it as a type of very thin plywood (I would love to get the ply rather than the particle), go back even further and I've seen really nice Japanese furniture from the 1940's or 50's with the super thin solid redwood panels (made from fruit crates no less

).
I can't and don't want a veneer. It needs to at least firm up when I glue and nail the frame to it. I just need to know the name of this stuff so I can buy it.

It's going inside my cab. I'm using it to partition part of the cab to prevent a metal pinball from accidentally flying into the elctronics or getting lost inside the cab. It will also double, in part, to guide some wiring back and forth.