I was thinking about what I could do for this task, and found inspiration in another task.

After some mixing and some wiring I made my first attempt -- it proved the concept, but wasn't nearly what I wanted.

(Of course, I nearly injured myself in the process. Not in the obvious fashion, oddly enough. I couldn't find a simple 9V battery, so I just used a power supply I had on hand. An old, high-current, huge-freaking-transformer-inside power supply. Which I nearly dropped on my foot.)

A couple slight adjustments in technique produced the basic effect I was looking for. It's not quite perfect, so I'll probably make another attempt, but I decided I'd left enough burn marks on the deck railing for one evening.