Hey, if you want a slightly different technique that will give you more detail (i.e. you can texture it or whatever), then try this: Sculpt your mandibles as above, then, instead of painting on the latex, cover it with plaster bandages (I'd suggest 1" wide, the stuff they used to make casts out of. Most pharmacies carry them and they're super cheap). Just cut it into small lengths (say 1-3" or whatever's needed) with scissors, quickly dip each piece into water*, run it between two fingers to get the exess water off, then apply. You don't need to use Vaseline or what; it won't stick to the putty (although it may leave tiny bits behind).
Do 3-5 layers and let it harden; this takes about half an hour. When a fingernail goes "Tic tic" against it instead of "Tunk tunk" then it's dry.
Pull out the clay, give it a wipe with paper towels, and then paint your latex inside of that instead. Do several layers, making sure each layer is dry before you do the next one (as you say, the hair dryer is your friend here), and then when it's done, just carefully pull the latex away from the sides and out, powdering as you go.
The nice thing about doing it like this is that you don't have to worry about drips; they won't affect the texture of the surface. And you can build up as many layers as you like to make them a solid as you like. For the tips just sort of pour a little in and swish it around. Just keep your layers thin or they'll never dry.
Plus you can make more than one with the mould (if you're careful), and if you sculpt the base in the clay and then cover that with plaster too, you can do the base and mandible all in one go.
I really like the paint you used; it has a really nice, rich colour. What brand/type is it?
has some really nice pro makeup with really rich colours and a lovely, smooth texture. The bonus is that it can be washed off with just water; but you can also sweat it off, which is a pain. But it's super nice to your skin, too; if anyone is prone to breaking out with heavy makeup on (I know I am) then check their stuff out.
Thanks for posting this!
*Important note: DO NOT pour this water down the sink after!!! Chuck it outside. Plaster will harden in your pipes as it doesn't need air and then the only way to remove the plug is to replace the plumbing. It's inert so far as the environment is concerned, though, so it won't kill your grass or what (although it makes a little bit of a mess until it washes away, so do it somewhere slightly discreet, like the gutter or on gravel).
**Not affiliated with them in any way; have just used it and really liked it. It's a very nice, usable alternative to heavy grease paints.