Mix well:

2 parts white glue (Elmers)
1 part Sta-Flo liquid starch

It needs to dry a little before it is "workable". It may not work well on a humid day. Store in airtight container.

Note: If you use Elmers School Glue instead of regular white it doesn't bounce or pick up pictures, but it makes a gooey delight your kids will love. Use on a smooth surface.