The Stun Droid is a watchful robot guarding the next building of the recycling center in Beyond a Steel Sky. You need to get past it to refill Leet’s moonshine bottle, but the Stun Droid is a diligent unit. To get past it, you would have to return to the building Leet inside and make use of the recycling center’s crushing unit.
There’s a console you can interact with to the left of Leet that you can turn off. After receiving the moonshine bottle, turn off the crusher control console, and you can safely approach the large crushing teeth. When you get close to it, use your crowbar to jam it. Your crowbar will prevent it from properly working. With it in place, return to the console unit and turn the crushing unit back on to raise the alarm.
The alarm will bring the Stun Droid away from its post to investigate what’s happening. The Stun Droid will knock Foster out if you approach it, so instead of waiting for it to show up, you want to turn around and enter the lockers behind the console to hide in them. Wait for the Stun Droid to scan both sides of the console, and then try to fix the crusher. While it’s working on the crusher, rush up to the console to turn it on. The Stun droid will be stuck, and you check out the next building. Don’t forget to pick your crowbar before leaving to go to the next building.