This is a 3D printable mechanism that utilises a standard microswitch, a cable tie, two m5 bolts, two m5 nuts, and a piece of string.

The string is connected to the end of the switch with a cable tie. When the lifter is stowed, the string is wrapped around the shield, and as it lifts up it unravels. This was used for FRC (first robotics team) 5985. This was used to detect when a climber had reached end of travel as an emergency stop procedure. Be aware that if the switch is not reset properly, it will remain tripped and the climber will not deploy.