It was important to me that the Rilovian race have both depth and breadth of variance, so I created both a class system and regional distinctions. Regional affiliations would be indicated by color, like in the Matoran universe, but I took care to not use the traditional, Earth-inspired Matoran/Toa elemental colors. (I also went with 5 regions instead of the original Matoran 6, just to be different, but later realized that Lego & Greg Farshtey had beaten me to the punch with the five main tribes of Bara Magna.) Rilovian class membership would primarily show up in size.
All Rilovians would share high, wide shoulders and a neck position that's forward of and below the typical humanoid anatomical detail. I also took care to minimize sharing of mask types between characters, just to make them seem that much more varied.
In each of the photos below, the representative individuals are lined up by region -- left to right, the Tiallo (air), Foran (rusty earth), Nofi (bright green inland sea), Rallo (sun), and Mikau (forests/wood).
After Gelaeus, these guys were first Rilovians to be designed, and coincidentally, the order I built them is the same order they're arranged below, from left to right. I tried to make them as distinct as possible. Only the blue & red individuals have similar weapons (swords). The yellow guy has a counter-balanced spear which you can't see here, but shows up clearly in The Lunacy of War. The blue and yellow individuals share the same basic construction, but the rest are unique. The silver-streaked masks represent double-forging, something afforded to the best warriors after a certain number of victories in battle. Behind each mask is a Metru head. Yes, the Telluris mask is mounted to a Metru head too.
I think I spent more time coming up with the design for these guys than any of the other classes. They're all constructed basically the same, with the exception of the Rallo & Mikau legs. I spent most of the design effort figuring out the right amount of color and the appropriate mix of light vs. dark.
These guys were easy; they practically designed themselves. I'm guessing this torso design has been arrived at by quite a few people before me, as it's really straightforward, based around an upward-pointed Bohrok foot. The fun thing with the construction of the elders was coming up with their ceremonial staves. Most use Bionicle minifig parts, and my favorite are the Mikau and Tiallo ones. Character-wise, I went contrarian with the Rilovian elders by making them "simple-minded" rather than incredibly intelligent, reversing the Matoran theme. In doing so, though, I was able to expose an unexpected form of wisdom, better explained in Colors of Life.
Ah, the big guns. I didn't want to make a lot of Giants since they're rare on Rilovi, and to be honest, I also feared that I'd have trouble finding enough invertable masks to form different heads. I could have just used Gelaeus, but I wanted to wait to introduce him, so I used this Mikau example in the beginning of the storyline. Again going against the grain of typical Western fantasy, I made these big hulks gentle giants of exceptional intellectual capacity. Rather than being menacing warriors, they're the super-geeks of Rilovi!