Koji "No. 63" of Laylax talks about the made to order Proto Gear Arts P90 Stealth Upper Receiver which is compatible with the Tokyo Marui P90 series. It might fit with the Marui P90 clones, so better check first. This is a 3D printed lightweight upper receiver, reminiscent of the popular "XF50 Tri-Rail".
Laylax's Koji "No. 63" presents the Proto Gear Arts M4 Upper Frame Hot Rod Style that should be available this month. The M4 upper frame, designed with the ultimate survival game in mind, eliminates all unnecessary elements for a streamlined and lightweight build. By integrating the hand guard, charging handle, and bolt forward assist knob, significant weight reduction is achieved.