A frame would be difficult (although not impossible) - but it would be expensive, perhaps prohibitively so.

Go buy yourself a small sheet of electroluminescent panel, a cheap inverter and some wire, you can wire the sheet up in 15 minutes, then you can play around with it to see what is possible, it can be cut to any shape you want (once you don't cut the connectors to the power supply off) rolled into a tube or folded however you like, it is pretty robust stuff and difficult to break/ruin - for example if I were to take a hammer to my seatpost above and give it a good strong smash, I would have a dented seatpost but the light would be unaffected.

Whatever you do don't forget to tape over all cut edges with something like sellotape - otherwise you will get a mild electric shock when you touch those edges ! And don't forget to unplug the power before cutting, you don't want to be like me and throw a pair of scissors across the room from the shock