Thanks, Radagast. I thrive on lots of encouragement and a bit of constructive criticism (from time to time) so really appreciate your comments.
I'm thoroughly enjoying learning to sculpt on this scale and in such detail. It really is great fun and one project just leads to the next because my mind is buzzing with ideas.
ProCreate, green stuff (kneadatite) and milliput are the putties that I'm becoming familiar with and they all have their uses.
Milliput is cheaper and I find it harder to handle. It doesn't hold detail so cleanly but it is really easy to smooth. If you add some water to tools, it behaves a little bit like clay and can be smoothed really nicely. Milliput is a pain to prepare. Sure, it's easy to mix it, but it's very sticky and leaves a coating all over one's hands. Being an irritant, it's a great idea to wash hands immediately after mixing, before continuing to work with it. One great benefit of milliput is it is easy to file, sand, drill and cut when it has cured. You can't do this very well (if at all) with gs.
Green stuff is a bit more expensive (especially if crazy enough to purchase it from gw stores! Get it on eBay - 36 inches) and I still haven't really got to grips with it (apart from sculpting scales!) I don't have the skills yet. I find this extremely difficult to smooth and blend. It needs to be stuck to the model within two minutes to adhere properly.
It's a pleasure to mix because it is not sticky and leaves no residue on the hands. Again, it's a good idea to wash your hands. Don't lick your tools to moisten them... just get a glass of water and dip them in that.
ProCreate is more expensive still, but you get what you pay for. It is very easy to mix and sculpt with. It's far easier to smooth than gs but not as easy as milliput. Procreate is amazing at holding fine detail and is less rubbery than gs. It yields better to tools. I always find I'm fighting with gs.
I hope this helps any budding sculptors. The best bet is to try some of each and see what you think. For my next halfling hole I will use a mixture of milliput and procreate for different parts of the model.
Cheers!