Hi, I have had a couple inquiries about where to get the flexible silicone blanket. They can be bought at
http://www.omega.com/pptst/SRMU_HEATER.html and scroll to the bottom of the page and put your dimensions into the part builder. It takes about 6 weeks to get it. Oder a 5 watt heater, that is plenty hot. When you wire it you must use your own judgement, but mine is just direct with no reostat or controller. Mine is 6 by 36 inches and I use it to make guitar sides also and is 1080 watts. I think a good size for making bass sides would be 8 by 11 and the wattage would be less, I think. It is a very good idea to put a hardware store timer-shut-off on it so you don't space out and burn down the shop.
If you want to make a bending form shaped like an oval or something, I think a wood form would be fine and you can order the blanket with pressure sensitive adhesive.