User blog comment:Alextheawesome/ATSD promo/@comment-4101140-20110628140540/@comment-4101140-20110628170057

@Alycia: That was my guess.

@Alternate Phineas: After going through a list of all the big ideas that I know will be appearing during the robot riot scene I realized that they were all inventions that Phineas and Ferb technically still have or were simply lost but were never destroyed, so I'm assuming that they've just been storing them somewhere (possibly in some sort of storage facility that they built beneath the house).