Tonight's model is Beyond Global's RX-78. It's in Prototype Gundam colors.
Rather than leaving it as is, I've mixed it with the old 1/144 Prototype Gundam kit and the HGUC Gundam (using the backpack from HGUC and the holster parts from the old kit) to make it as close to the Prototype Gundam's shape as possible.
That said, I gave up on modifying the lower arms, which are unique to Beyond Global, and the ankle armor, which has a unique attachment method.
The beam rifle is based on the HGUC one, and was made by transplanting parts from the old Prototype kit.

Beyond Global (prototype color) | ヘイカユウジ's Gunpla works