I don't know ya know, it's strange. the original suit was done in water clay. so, I figured why not, on the original foam pieces you can kinda see that it had been done in water clay groomed with a sponge, or something. But I suppose the same effect could be done in an oil based clay. just don't do the automotive sweeping thing too much, use a solvent instead of water. Down side to water clay is the constant maintinece of it all. either too wet, or too dry most of the time. Gotta keep it wrapped in something wet, and keep checking to make sure that doesn't dry out, can't just walk away forget about it all. Up side is it's quick. If you know the piece, or know exactly what you're after in a sculpt, you can get the whole thing done much quicker.