The only pre-existing one is the MP ZZ in the upper right. The other three are just custom variations on an MP Nu (the original Pixiv post goes into those in greater, but unfortunately smaller detail). There's a Gundam-face type in the lower right, a GM-face type on the lower left, and a sniper-visor type in the upper left.
They borrow a few design elements from Jegans and Jestas but there isn't a Jegan or Jesta here exactly.
