Not finding a suitable light (or wanting to take on the challenge of making one), I purchased two pairs of Glo Gloves which have pieces of Reflexite retro-reflective vinyl sewn on.

FYI: there are two styles available for cycling; Sport (palm padding, reflective back) and Original (reflective front and back). Both can be worn alone or stretched over cycling gloves. I bought the "Rider ~ Packet" so that our tandem team has a Sport pair for the captain and an Original pair for the stoker (who does most of the signaling).

Bruce Rosar
Not associated with "Glo Glov" (other than being a satisfied customer