Use the mats with magnetic letters.
Book: Chicka Chicka Boom Boom
by Bill Martin Jr and John Archambault
Illustrated by Lois Ehlert
This one uses less colored ink, but I made both for my grandson.
I borrowed the book from my grandson and he said "hey grandma where are you taking
my Chicka Chicka Boom book? He really liked the book and I can't wait to do the mats with him again.
This is my youngest grandson.