I was just wondering what kind of mechanism people tend to use when designing these. I ask because it occurred to me that perhaps a "Multiskewb" could be made using one of these built up around a Skewb mechanism, similarly to the Crazy 4x4 I which has a 2x2 inside of a 4x4.

Generally tetrahedral cores are used, but in the case of a Circle puzzle, an octahedral core would probably be better. Although I can't imagine a Circle Elite Skewb being very good looking. The Circle Elite Skewb and MultiSkewb would also be very different puzzles.

Ah, for some reason I was confused. Yes, a Circle Skewb and a Multiskewb would be very different... which makes me wonder if a true "pure" MultiSkewb can be built.

Like this ?