Actually, hot water will not work with styrene plastic - it is too dense for that. I tried.
However, what I did discover since writing the article is that using a heat gun makes it even more comfortable - you do not deal with an open flame, the plastic does not melt or emit fumes, but can be shaped into anything you want. A heat gun is an industrial version of a hair dryer, essentially. Can be had for under $30.00 and you exercise more control.
