You can often find, or could find, nitrocellulose lacquer in hardware and paint stores. For instance, I have some Sterling clear lacquer that has nitrocellulose, and a spray can of Deft Clear Finish that lists nitrocellulose. I don't know if they're as good as nail polish., Beacon 527 lists nitrocellulose as an ingredient. I have made some successful igniters by mixing graphite with it and applying to two very closely spaced wires, followed by something similar to Richard Nakka's RNX* as a pyrolant and protective coating. I think it takes a bit more zip than you'd get from a 9 volt alkaline, though. I actually wind two magnet wires together, glue them together, sand off the insulation, and apply the coatings. It's impossible to sand the insulation that's actually between the wires. The only thing is that my VOM doesn't understand that these are conductive. It waffles, and then decides the resistance is infinite. However, when power is applied, they work fine. I wonder how Beacon 527 and a bit of KNO3 would work as a pyrolant. Incidentally, some other glues have nitrocellulose. I think Duco is one of them. Then there's something called Fab Tac. And nitrate dope.
A traditional plasticizer for nitrocellulose dope is castor oil. Perhaps a drop or two of that per ounce would keep things a bit flexible. Also camphor, but I don't know where you get that. I have heard rumors of oil of almond oil (not almond extract), wintergreen and even mothballs used as plasticizers, though I'm guessing the latter eventually evaporates and disappears. There is also something called Flex-All.
