In article , "Huge"
says...
(Steve Firth) writes:
Huge wrote:

Anyone got any good ideas on how to fasten a wooden side panel onto a
bath in such a way that the fastening is; invisible (from the outside),
adjustable (it's bound not to be level) and removable (should I need
to get at my scabby plumbing)?

Velcro, just to give an alternative to magnets. You can buy in in
stick-on lengths at most DIY places and since I don't trust the stick
on, I would bang a few staples through it as well.

Bingo!

I'd already discounted magnetic door catches, since they are designed to take loads
normal to the magnet, not axially, and this thing weighs several kilos.

So fix some adjustable feet on the back to hold it level.