Hello For start lets make base aka round cylinder which will be used as model platform, for motion and anchor:..like with tabletop models. Then lets begin skeleton with legs *used pictures are from sciencephotolibrary, I not created them and are here just to ilustrate what we talk about. keep in mind, our goal is not to make ultra HD skeleton model, just decent acurate shape, with good proportions. 1) Pelvis bones pelvis is a center of mass...well not for busty model with 1/5 of weight on tits, but in order to our skeleton, it is... it is our first and main bone. Its shape is crucial help, because lot models got issues with sitting pose and kneesto chest pose ...also pelvic bones should frame bottom/side of belly and kinda stick out alittle, especially when slim girls does kinky motions. note1: it is important to make decent articular socket, thats where pivot of legs should be and if made right it should dramatically help with natural leg motion note2: