The Stimpak Diffuser is a medium-sized, cylindrical device with a retro-futuristic design, featuring a combination of polished metal and worn plastic components. It has a central glass vial containing a glowing green liquid, secured by metallic clamps and surrounded by intricate circuitry and small, blinking indicator lights. The device is equipped with a nozzle at one end for dispersing the stimulant, and its surface shows signs of wear and battle damage, with scratches and dents adding to its post-apocalyptic aesthetic.