Drawing, sculpting or modeling realistic hands is one of the hardest parts in recreating the body.
Of course, you can use your own or another person's hand as a model, but that is not the best solution and, above all, you don't have the freedom to try as many poses and sketch them at any time you want.
To overcome that problem, you can get yourself an articulated hand mannequin. You can move each articulation modeling virtually any position a hand can be in, place it in front of you, and start drawing or sculpting. As many times as you want, until you are satisfied with the result.
We have to prepare each shipment individually as they are ordered, so allow us in 3-4 weeks for it to arrive in USA/Canada (to be safe) and 3-6 weeks rest of the world, though thy are usually delivered much faster.