Yes I know it's a not random. I need a long sanding block for sanding my body work but they are fetching silly money on the bay etc.

Any ideas on how to make one or get one cheaply.

I used I use a 20" one which was good.

I bought a cheap hardware store sanding block, to rob the spring loaded clips off.
Sanded/planed an actual block of wood flat.
Stuck 3 or 6 mm closed cell foam to the block
Screwed the clips on
Done!

Cheers

Fred W B

Never found long boards anywhere, always ended up making up with plywood --- a stiff one and one with a bit of flex for gentle curves.

Screwfix rolls of sandpaper, homemade longblock complete with handles like a plane, drawing pins to secure - locost heaven!