Hey dude,
on this one I have to say that I draw a blank- I have never experienced a single part putty....
however, the one that I know the studio use quite often is called 'wood putty' - used for filling chips and cracks in furniture... stinks to high hell and is toxic, sticky and generally nasty, but great for using in a variety of ways.. it chips, sands and carves well.
Otherwise, I would be very interested to hear what other people use?
cheers
WARHOUND