I'm interested in how folks come up with their Things. Do you have a preferred technique? Do you find an image or build a creation around that, or do you take your inspiration from the movies, books or comics?
I have a number of techniques. The first is pretty simple, in that I take a classic monster and try and re-imagine it. The "Death Shroud" (as seen in the "New THINGS" thread) simply arose because I was thinking about the classic mummy and wondered what happened to them once their flesh and bones had turned to dust. Occasionally I'll look at the mythology of a classic monster - the vampire - for example, and try and think about things in the natural world that might do something similar. Nocturnal flight, the sucking of blood from a slumbering victim, themes of disease and infection; all can equally well be applied to a mosquito. Would a swarm of monstrous mosquitoes the size of cats freak out the players? Sure, especially if they're expecting Dracula. How about a man-sized mosquito beast, arising from the foetid swamps to drain the blood of helpless children, infecting each of them in turn with a horrible malaise? Could be fun, especially if the PCs are all kitted out with crosses, stakes and garlic!
The second technique is a little more complex, in that I build a creature using the basic principles of evolutionary biology. First, you identify a niche - literally a space in the world for the creature to inhabit - then you create something to fill that space. You work out what it eats and why, what it's behaviours are, how it has avoided detection, what it's relationship to the world is (does it have a natural predator?), and if it's intelligent, what it wants. Despite the fact that supernatural creatures don't have to be subject to scientific laws, this technique works for them too. In fact, supernatural creatures are even more terrifying when you discover that they've adapted to prey on us...
There's a wonderful Ramsay Campbell short story called "The Brood", which illustrates this technique perfectly. In the story, the protagonist sees an old woman dressed in black who continually dances around lamp posts at night. At the same time there's a drop in the numbers of local homeless, stray animals etc. Eventually the protagonist invades the woman's home in search of a stray animal he's seen her abscond with, only to discover that she is actually a form of giant vampiric moth, perfectly adapted to live among humanity without being noticed...
Does anyone else have any favourite techniques for monster making?