From Muppet Wiki

In 1993, Playskool released three kits of puppet toys based on the Muppet Workshop's Whatnot puppets. Each set came with a set of body parts to create your own Whatnot character or monster, not unlike the way real Whatnot characters are created in the workshop.

The first set, "Muppet Puppet 'n Parts", came with parts from which puppets could be built, including arm rods for performing each unique creation. The second set was a simpler collection of fabric pieces, while the last kit was made to work with Play-Doh and included pieces used to make Kermit and Miss Piggy.