One of the big jobs for the re-build project is resealing the wing tanks. This model of Cessna 206 has "wet wings", basically a section of the wing is put together with sealant and is used to hold the fuel inside of the wing. This is different than a car which has the fuel in a separate purpose built tank. Other options on airplanes are "bladder" tanks made of rubber.
Almost all airplanes, including airliners, have the fuel tanks in the wings. Really small airplanes like Aeronca 7AC Champs have a tank right behind the instrument planel. But those airplanes don't have a second engine, flaps, a nose wheel, starter, or an electrical system... that is why they are much fun to fly.
After cleaning out all the fuel tank sealant, new sealant must be applied along every seam and over every rivet. (Its the dark grey stuff) Let me tell you, this stuff is SUPER sticky! Once we get done with this wing, there is one more to go!
Dave and Nathan have been painting control surfaces. Hot and humid weather can make it a challenge to get the paint to come out right. It takes a full day just to spray the primer and then the white top coat after that. Having worked in a paint shop, I know that prep work is 95% of a good paint job... but the last 5% can still ruin a good paint job.