Strip heaters are not common everywhere and to buy one to build just one ROV is a bit too much.
After Christopher Plymire added the picture of his home built heater, I took the chance and went for that solution too.
I bought some constant resistance wire, used a wooden board, some tin foil, screws and household extension cord wire to build an improvised strip heater, just big enough for the OpenROV body.
The tin foil is folded a few times and acts as both reflector as well as protector for the wood. The wire is wound across the screws and soldered to the wire from the power supply (the resistance wire is coated and the soldering breaks that coating).
Christopher mentioned in his post that you could use a standard PC power supply and as I had a spare ATX PSU I went and used that one. Now, to use it without a mainboard, you have to pull one connector to ground (the green wire). Otherwise you don't have anything on the 12V line. Beside that, many tutorials tell you to connect a device (as a HDD) or resistor to the 5V connector. Otherwise the PSU could get damaged.
The pictures below are from my test bend, but it worked with the blue acrylic too.
I just put the acrylic over the hot wire for about 3 or 4 minutes until it gets a bit soft. After 2 more minutes, it should be okay for bending.
And here the finished version: