Wrapping paper

Today I made my first repeat pattern for a funky screen printing studio called Frinton Press.  They have a yearly wrapping paper design competition, and I stumbled on to their call for entries just a couple days ago.  Here is what I submitted.

I know there's an easy way to do it on Illustrator or Photoshop, but my googling skills were just not up to the task and I couldn't find a tutorial.  But I did find this wonderful analog how-to by illustrator Julia Rothman on the Design*Sponge website, which you can see here.