Line launchers are devices that have been used for centuries for maritime rescue operations. The typical implementation is the use of a gun, rocket, or mechanical launcher to hurl a grappling hook or flotation buoy for stranded ships and overboard sailors. Microgravity offers analogous use cases, ranging from microsatellite operations to space debris interception. As such, the Lachesis line launcher is a handheld device that is purpose-built for microgravity applications. After the user pulls the trigger, a laser ignites a smoothbore rocket-propelled projectile which carries a nylon line behind it. Angled threads in the barrel provide the spin and stability that is typically only achieved by conventional rifling. To reduce weight, most components are 3D-printed out of polylactic acid (PLA), a biodegradable and light plastic. With a total weight of 68 g and a projectile kinetic energy of 0.127 J, the Lachesis line launcher presents an effective, potential option, even with contemporary operational constraints. The design combines several proven principles to demonstrate the viability and use case for an updated line launcher in orbital operations.