Recently I was building a prototype for a LEGO tank chassis and I tested it, but my finger got caught between the gears, resulting in my finger getting cut. Are there any ways to prevent that from happening?
Here's an idea for a stop switch using a remote control and one's wrist.
Place your wrist on the switch to start the motor. With your hands free you're still able to carefully adjust your running gears. But what if something (or someone...) gets stuck?
Just lift your wrist and the motor will stop immediately. No need to quickly flick that switch on the battery box anymore.
If your geartrain contains z24 gear you can substitute it with z24 clutch gear. It has built-in safety mechanism - it would slip under certain toque and as result of this it will stop transfering motion if gears placed after it would stop or get blocked.