MP-05 was done by Hisashi Yuki - that info will become widespread when the interview with him is translated; cause SydneyY mentioned briefly in a post on TFW, that Yuki states MP-05 was apparently designed in a mere 12 days!

MP-3 was also initially Kobayashi, then amended by Kawamori - then Kobayashi returned to it for the MP-11 modifications. Apparently that was motivated from dissatisfaction with the colouring, once the MP line was (more) clearly established to be about being accurate to the G1 source material.