I'm supposed to be doing work
Major Miners, a concept that's for some reason stuck in my head. Must be all them video games: the general style and milieu was indeed inspired by Spiral Knights.
I don't precisely follow the usual naming conventions for Pinkie's sisters.
Ingrid, or Inkie: The eldest of the three, a serious warrior dual-wielding a mattock (pickaxe for the uninitiated) and sledge hammer. Her Tenacity in combat is enhanced with Runes of magic power. I use Octavia's design for "Inkie" because she provides a better contrast to the other girls, but her colors do include some of Inkie's palette; the cool green pops with her warm greys. Her dual-wielding setup was inspired by Octavia's instrument and bow.
Pinkamena, or Pinkie: The middle sister, a jovial odd duck who uses bombs and a hand cannon to dispense explosions at a distance. She practices Alchemy to imbue her mechanical Arms with elemental power. Pinkie's glasses and bottom-heavy silhouette give her a more "grown-up" appeal to play up her intelligence, as opposed to the child-like designs of most interpretations.
Bianca, or Binkie: The youngest sister, an earnest worker with surprising strength that lets her wield an oversized power drill to tunnel through the ground, and lift and throw objects many times larger. Her feats of strength are fueled by Guts and augmented by Spirits of the earth. Binkie was the first sister I ever drew, but also the most difficult to make unique; she ended up being the tomboy. Her pale hair and skin contrast against her blue palette.
Each sister has curves along which they can improve their abilities. In addition to the unique specialties noted above there are three core curves: Bounce is speed and stamina; Heft is strength and balance; Shape is precision and skill.
Inspired by My Little Pony: Friendship Is Magic