This right here is why people don't like to let me near power tools Is it weird that I instantly thought AJ being more steampunk then electric made sense since she's out in the fields most days and can't recharge like the others?
I rather enjoy this series, and how you managed to work elements of their personality into their construction: Applejack is a hard worker, characterized by her droid's internal combustion and gears. Twilight's full of science and magic, so she's a holographic construct. Rarity is the model of elegance, so she's sleek and rather reminds me of GLaDOS. Fluttershy is (relatively) simple and beautiful. Rainbow Dash 2.0 is shaped similar to either a Gundam or Metal Gear RAY, which fits her kick-ass-take-names spirit.
Pinkie Pie... Well, who knows with Pinkie? Angles here, contours there, and that cannon.
LBX. Go google it up. ^^, It's an interesting little mech idea. Technically, it's geared towards children but it's still awesome. ^^, I suggest giving it a looksee if you're into robots and mechs and stuff.