I'm still using a quart can of Parks Sanding Sealer that I bought at Hechinger's.....
Minwax makes a lacquer based sanding sealer.
As for shaping wood roof sections, that was just part of building a craftsman kit - still is. And, it's pretty easy to do - all you need is a 4-in Hand, a couple of sanding blocks, 60, 120, 320 grit, some sanding sticks, and patience. I actually short cut that process a bit using a 4" upright belt sander......