Some background: I'm making two chess sets, connected via internet. The pieces have magnets, and the board has magnetic sensors, so when a piece is moved on one board, it is dragged with an electromagnet to the right square on the other.
The problem: I laid down some veneer to make the checkerboard on 3/16" plywood. The maple was slightly taller than the walnut, meaning that the walnut didn't get clamped as nicely as I would have liked. I knew this before gluing, so I put a towel down between the board and weights to more evenly distribute the weight, but it wasn't quite enough. The final product is mostly really good, especially after some sanding, but there are several squares with bubbles in the walnut that I can push down ever so slightly. I can't redo it because the other side of this board has 80 sensors which took many hours to put into place.
The question: Is there any finish that would work well to soak into the wood and bond the walnut to the plywood where it's coming up? Some kind of epoxy resin? Or would regular varnish do the job? Bonus points if the finish is low friction against felt :)