Once Upon a Child in Downtown Disney or Tatoonie Traders (exit of Star Tours ride) in Hollywood Studios.Ooo, where do you do this? I haven't been to Disney in 7 years so I'm unfamiliar with this but it sounds like something my boys would LOVE.
I highly recommend it. Not only did my boys have a great time choosing and assembling the pieces, it's good value for the money. We've had ours since 2011, and they've held up well over numerous Jedi vs. Sith battles.