I realized some time ago I was going to have to make my own floats, as the many models of seaplanes available are all from a later period, and the floats are such a different shape that I could spend a lot of money on a lot of kits and never find one that would work. I had some Styrofoam packaging I tried, but I seem to lack the skills to work with it. I ended up laminating several layers of thick plastic together.
After letting it dry overnight I spent several hours today with a grinder attachment for my Dremel tool, and a few more with a sanding block.
It's going to take a lot more time before it's done, but they're slowly taking on the right shape.