At the moment it's wet and dry to 1000 grit, then polished up with acrylic polish.
Once the electronics are back in and I can test it properly, I may sand it all back to the wood and start again.
I've honed my technique for applying the glue, and I'm pretty sure the board was, somehow, flatter than the expected 20" radius when I started this.
Which is why the edges have gone through.
So my plan is:
See how is sounds, if good:
Sand back and re-radius the board.
Redo all the glue, wet and dry to a much higher grit and polish more.