For a small musical instrument I need a thin sheet of spruce (1.5mm). Normally I’d just buy a guitar or lute top, but for this one I need the highest quality I can get, with very narrow rings. So my idea is to saw down a blank for a violin top (25mm at its thickest point). I need to do this with as little waste as possible, because a good spruce top can cost 100-300€.
Is there a way I can do this with hand tools?
A good handsaw and years of practice will do it. Cut it to more like 2mm or more and plane it down to your final thickness. But it’s not easy! Good luck
Yep, this. Chisel, glue up, or carve a recess into a larger piece of scrap plywood to use as a jig to hold the work piece while you plane it. Make the recess the exact depth of thickness you need and you can plane it perfectly to thickness.