Here's a trick I learned and wanted to share about painting / varnishing something on both sides in a hurry.
One normally has to do one side, allow it to dry & then do the other side.
(unless you hang it from a hidden spot)
Not sure if this has direct application to guitar building, but I'll leave that to your own imagination.
I was making a braai table.
Out of interest: Rhodesian Teak border and Meranti middle bit.
First trick is to make my little wooden "pyramids":
These have a tiny point which can be used to suspend the surface.
It makes a tiny ding in the varnish which is easily touched up.
And from the top. The bottom had already been varnished at this stage:
Made a massive reduction in the finishing time.