Advice for leading a sculpting activity? Which materials are best?

Hi teachers of reddit :) I'm working on a project for a tabletop role-playing game where players can sculpt little characters as they play. Since there's really more of a precedent for this kind of thing in the classroom, rather than at the gaming table, I thought perhaps this sub can help me. The type of thing I'm planning will be with other adults rather than children, but it will require setup and cleanup in a shared space, as well as consideration for not making a huge mess.

I'd also love any organizational tips, or advice for encouraging creativity at the table. I myself have been sculpting for a long time but I know that leading others will be a whole different ball game. I want to be able to create a fun environment where we can all share and workshop our cool ideas.

If you've ever had a creative project in your classroom that involved sculpting or any other type of 3D arts and crafts, I would love to hear about your experience. :)