Originally Posted by
sewsalot
I have a suggestion. Instead of a cardboard insert, how about ironing some freezer paper inside to stiffen and keep the fabric from shifting when guests decorate it. Then you can peel it off later.
Have to agree with sewsalot on this. Using freezer paper is the way you want to go. I have done t-shirts for the Grandkids using watercolor pencils, or crayola crayons with a freezer paper backing. Heat set when done & wait at least 24 hrs before washing.