I read about people using nail polish or lacquer, but, using a core makes assembly a whole lot easier, stable and consistent. If I remember correctly, my core height is about 1/8" greater than an off-the-shelf seven string plastic bobbin, so, I can get plenty of wire on there.Another solution I've seen to eliminate the shorting against the pole pieces is to coat them with nail polish. Would take up less room than a core, so you could fit more windings on there if you were trying to make an over wound pickup.
I'm just wondering now if it would be better to cannibalize an old sewing machine, or if it would be better to just buy an electric motor and start from scratch... probably the sewing machine :lol: I don't think I'm handy or smart enough to build from scratch :lol:
Starting with an old sewing machine puts you two steps ahead because it already has the speed control and a place to mount the bobbin. Just a thought....