You'd need the services of a proper skilled sculptor if you want a decent looking figurine. Trouble is getting hold of such people, telling them what you want and then paying them to do it.
They need to start with an idea, then onto rough sketches, start building up a wireframe manakin and only then onto fleshing it out with putty, normally working in short bursts due to the limited working time of the putty. The casting of them was traditionally done in white metal but some have now moved onto resin and some designers sub contract the casting to them.
I've tried it myself and it really is a hard skill to master. Some of the best ones are really brilliant at capturing delicate nuances on facial expressions, slight poses and generally putting in alot of extra detail. Takes alot of dedication to actually make anything that seems like a human being!
Michael W