After tripping over my tea-kettle-on-a-hot-plate steaming setup one too many times, I looked around for a better mousetrap that wouldn't break the bank. What I found was a neat little wallpaper steamer from Wagner. It's completely self-contained, about the size of a car battery and won't spill if you knock it over. With an 11' hose, you can locate it well out of the way, anyway. It holds a full gallon of water, heats quickly, runs for over an hour and produces WAY more steam than my kettle does. It also has overheat protection in case it runs dry (I fried the hose on my kettle rig once when it ran dry). If you need more capacity, it should be a simple matter to connect a drip tube from a larger water reservoir. Obviously, it can also be used for steaming wallpaper, or fabric on an SOF, for that matter.

The Wagner 705 steamer is available from Home Depot and others for ~$50. There are cheaper solutions (like my spill-prone kettle rig), but this is the best steam generator I've seen for the price.