A zip begins with the letter z - but what else? Get the kids to brainstorm some "z" words and then model them out of playdough. I feel a playdough zoo coming on ...
Alphabet begin with the letter Z playdough mat - Log in or Become a Member to download
I'm not sure how you model an X-Ray out of playdough - but perhaps the kids can come up with a way? You might relax the rules with this playdough mat and ask them to model words ending with the letter x, too.