Here's the original Pinterest pic and link.
Here's my version. And, like all Shrinky Dinks, imo, sometimes it works and sometimes it doesn't. I tried another one and it didn't melt quite flat. But really, how fun is this to do after a party? Clean your cups and draw away!
FYI, if you use the scraps of the cup to make other things, keep in mind that the shape of the cup keeps them from melting normally. For example, I punched circles and heated and they became oblongish and weird, as well as just shrinking.