I'm currently building a God Gundam based on the MGSD Freedom. The head is made from MGSD, with the antenna, cheek ducts, and Vulcans from BB God temporarily attached with super glue. The shoulders are from Hi-Res God, with only the connecting parts transplanted from MGSD. The backpack is made by cutting off the canopy from an RG, creating a joint with plastic sheet, and attaching it with super glue. The rest of the exterior is temporarily attached with adhesive.

MGSD Modified God Gundam | スミス's Gunpla works