This is my theory on how the Toa came to be...
...the storyline differs from the real one though...
Makuta is trapped in a sphere of protodermis in his lair, his sons figure that to release him, they need to give the blood of The Seventh Toa as sacrafice. So, they capture Takua(its still a Toa's blood) and slit his wrist, give the blood. Takua still survives though. Makuta gets freed.
Toa Nuva vs Rahkshi. Toa win. Takua falls into protodermis with the MoL, and becomes the ToL. Big fight with Makuta, and using the Power of light mixed with the Toa's Elements, create a wormhole with Taka and Makuta fighting inside it(the wormhole is a sphere, if you are inside while it is being made, it works only in the outer shell of the hole). The Toa, stripped of their Nuva powers making the wormhole, are sucked inside the hole covered in protdermis(this later forms the canisters). Now, rewind back to Takua and the Toa Stones. When he placed the Stones on Kini Nui, it created a beacon, a marker for the Toa's Time Travel journey to end. The Toa are actually jinni, or in laymen's terms, a thing that has no proper beginning due to Time Travel.
Fits in kind of well, don't you think? Post your comments please.
D.C