Made for the challenge: Eeveelution Exploration. I finished just in time! Done on Paint Tool Sai, taking approximately 3 hours. Dedicated to Linku-kun for hosting the challenge!
To evolve an Eevee into a Draconeon, have it reach maximum happiness while holding a Prism Scale. Pretty much the same as evolving Eevee into an Espeon or Umbreon, but while holding the item used to evolve Feebas in Gen V.