Had to interrupt the Doppelcaster making for a few days because of performance tonight (yes, the performance for which the guitar was initially planed - didn't make it!)
Thought I would post a few some beginner's considerations. First, the polyurethane finish goes deeper than I thought, I made a first sanding that felt good enough, but when I tried wood stain on it, it proved not enough and it needed a few extra hours sanding to reach the bare wood.
I learned a few things doing this: it's way better to work in your basement with protecting goggles and dust mask than in your living room (yes, I can be dumb sometimes)! And you shouldn't spend three hours machine sanding in the morning when you rehearse music in the afternoon - I actually still have sore hands one week later! And wood stain is not the best solution for refinishing, because it requires a perfectly neat wood.