Prime Time... I made this custom last year [2016]. Mega Prime has some Gundam missiles added to his shoulder-pads as well, thus resembling Ultra Magnus.
The base figure was the Arms Micron "AM" Optimus Prime.
He was fully recolored in the original color scheme, making him more vibrant. I also customized the regular double-barrel handguns that are made by third-party company Dr. Wu, thus making them longer and sturdier with some household items [such as the parts taken from clicky pens and spare Gundam parts]. And I colored those new handguns, painting them black and silver with acrylic paints. And I had to put some putty into the mouths of the new barrels, before coloring their cores gold, within the nozzle. Some of his chrome parts parts were highlighted with silver sharpies. Smoke stacks on his back are from Gundam fodder parts.

Additionally I gave Prime some new shoes... heftier feet created with painted putty, which can carry more weight and help to balance him more readily. A ton of nail polish was added to his legs at the hip joints, which were initially super-loose. He doesn't Transform, since I purposely made him an upright articulated model.
More pics of this guy are available in my DSNG Blog...