One of the best contests for airsoft gunsmiths, the Hyperdouraku Custom Airsoft Gun Contest, just had the results of their 2023 edition announced. The revered Tanio Koba leads the ceremonies in announcing the winners together with the sponsors of the contest. We highly recommend you visit the page as the creations are always interesting, showcasing the efforts and creativity of airsoft gunsmiths in Japan.
One curious custom work submitted as an entry for the Custom Airsoft Gun Contest on Hyperdouraku is the Heckler & Koch G11 by Kato. This is an AEG based on non production protoype G11 assault rifle that was designed from late 1960s to 1990. Whilst a thousands units were made, it was never brought to full production.
Read further details of the G11 airsoft here (in Japanese).