Op chose on 9 October that everything alive is 3D, and asked for the vehicle in his own words: "we should explore reusing a same rig for as much of it as possible and instead attaching bones and skeleton partials/sections dynamically per genes like we already do in 2d I believe". The canon row is a_creature_is_a_3d_body_off_one_rig_with_sections_its_genes_attach. This page tries it: five creatures and a four-armed folk, each the villagers' rig re-rested for a body plan with whole sections of skeleton attached where its genes call for them, each section a chain of bones with a mesh of its own, made once and fitted to what it hangs from. Everything is drawn live here by the code beside this page; NOTES.md says what holds and what does not.
The page before, which tried parts (a tail, horns, a second arm pair) and a second base, is kept whole as off-the-rig.html, its notes as NOTES-creatures-off-the-rig.md.
Three steps, each from the genes. A body plan is a mark the genes fold to (four legs on hooves, four on paws, a bird, or upright): the villagers' rig posed and that pose held as the rest, the torso pitched at the pelvis and the waist, the legs turned back under it and crouched, and what the plan does not keep (the villager's arms, its neck and head, its feet) cut from the drawn mesh. Then the sections: a thorax closed over the villager's ribs and carried forward, a fore limb pair hung from it, a neck and a head, or for a bird an egg of plumage over the torso, folded wings and a tail fan, and below the villager's ankle a cannon and hoof or a bird's tarsus and toes. Each section is fitted to what it hangs from the way a garment is fitted to the body, so it follows any shape the genes give its parent. Last the parts of the page before, a tail or antlers, now hung from a section as well as from the body.
Each body three ways: standing from the side and from three quarters, a stride of twelve steps from the side, and at the game's own scale, 60 pixels to a villager's height, beside the CC0 deer base the page before brought in where it applies. Then what it is built of, its bones, and plainly whether the sections reach it.
The deer and the moose of sections laid over the CC0 deer base given the same genes the page before used, side on at 40 pixels to the metre, aligned at the bottom centre of their boxes. Orange is only the body of sections, blue only the deer base, dark both.
From probe.cjs, committed with its numbers in probe.json: a herd of 1, 8 and 32 posed and skinned twelve times a second and drawn at the game's scale, in milliseconds of this page's one JavaScript thread per creature per second. This is the cost of this page, not of the game, which skins on the GPU; it says how the bodies of sections compare with the deer base and the villager on the same code.