Essentially incorporated the parts (front cocking tube/sight, cocking handle, eye bolt, mag release catch, receiver void fill, lower) from the GSG 5-522 conversion kit (ebay) with a scavenged rear diopter sight, shroud, push pins and metal rear stock from an old airsoft one. The front hand guard was from a CGN member who sells printed ones on EE with some functional hand guard pins molded in to a built up plastic epoxy base.
The front eye bolt was drilled an epoxied in, all rails removed and the receiver sanded down to round, and some plastic epoxy built up to fill in some of the gaps. The rear sight base was sanded down from the existing base. Took about a full day to figure it all out. Its just plastic after all so you just have to have a resilient disregard for the end result/resale value of the gun
At this point just deciding on if I want to go with a full rear stock over the extended one which would require some easy surgery and some tubing to finish the shroud... and probably a rotary mag
The pictogram stickers are available on Redbubble.