Buy a large lot of constraction parts from eBay.
Buy either '01 Tahu, Kopaka, or Lewa.
Make a Constractionformer.
I’m actually currently working on one, though I had to scrap what I got because I couldn’t find a way to fold the arms and legs in. At least, not a way that looks any good.
Edit: I got an eye on a LEGO lot that’s just what I’m looking for, so that’s good.
Edit again: It’s mine! I got a constraction lot that seems to have all 6 '01 Toa, plus some throwbot parts!
Complete an entire collection of everything Bionicle, including the random toys like the Barraki squirtgun. I might need to cheat and use Shapeways for the Platinum Avohkii and G2 14k gold masks.
Add to that a complete collection of all the combiner/alternate models.
Recreate all of the canonized fan-mocs such as the Dark Hunters and Rahi.
MOC all of the characters we haven’t seen a physical form of.
Display all of this on the walls in my glorious man-cave, along with a huge building station in the middle of the room for MOCing.
Someday I’m gonna collect every Bionicle set in existence. Then I’ll buy more so that I can make all the available Rahi combi-models, buy several Bionicle Master Builder Kits, and buy pieces to make however many Dark Hunters I can guess from looking at the pictures. I hope to make the ultimate Bionicle universe.