Well, guess what? We know what you're going to be doing on or about October 31st, and you don't need to build an outlandish machine to do so, because you can get most of these costume pieces at thrift stores or second-hand shops near you. File:Phineas Ferb Perry surfing.jpg You can discover how to create a Phineas and/or Ferb costume at eHow.com, and also find out about making your own Perry/Agent P outfit at Dabbled.org. Wondering about almost just about some of the other major characters on the show? Follow the instructions for each character as follows.