The Rainbownator 5000 can be crafted after getting the crafting-recipe as a gift. Players who attended the PAX-conference were given this recipe as a present. The recipe can sometimes still be provided by the devs for a short time - you might want to keep an eye out on the forums and/or Playful's twitter for that. The sword itself is not very strong, it does just as much damage as a Stone Sword. It merely has a unique look and a nice rainbow-effect when you swing it. To craft 1 Rainbownator 5000, you'll need (as of R26 in December 2015):