H8MS wrote:I think you can technically do a live action version with the actress wearing a green body suit and green screen editing software
Probably not, actually. At least I don't think so. Shooting a scene in this manner results in the ability to turn the "green" area transparent. However, this merely allows a background layere to show through. Since the positioning of the green area would change as the actress moved it would be necessary to make the background layer move acordingly. If you simply used a static shot, or even a moving video, of the mud, shot separately, it would not move or would not move properly. The result would be a visible edge where the foreground and background layers met.
On the other hand, I suppose you might explain the "edge" as a not-quite perfect invisibility.
A body partly submerged in a pit of mud WOULD create a deformation in the shape of the mud, but it would actually be in the shape of a mold of the body all the way down from the surface. If you had a series of body casts it might be possible (albeit pretty expensive) to produce a series of shots in which each casting was submerged to its top edge, so as to create a body-shaped hole in the mud. Aboout the only way I would attempt such a scene, however, is if someone else provided the molds. Even with that it would be quite an,....err,.... undertaking.