I based my method a lot on Doktor Zeit’s solution for “Tossball All-Star” -
“ These are melee weapons that resemble lacrosse sticks, you can find one of them very early to the right of the workbench in your ship. Passive creatures also count towards this, a lot of my kills came from Sprats, the little green lizard type animals. There are a few pockets of these alongside the outer walls of Edgewater, they will respawn after enough time has passed, if you crouch before killing them it will also count towards the 50 stealth kills achievement.”
The only variation I made was using the Prismatic Hammer found on Groundbreaker
*** Spoiler - click to reveal *** To the left of the big door past the security booth, there’s a room with some stevedore’s sitting in chairs. Climb up the crates behind them and on top of the white bunk things. There’s a hole that can be entered by crouching with a few outlaws inside. Deal with them and enter the door to the right, the hammer will be sitting in there.
and using TTD.
The only hangup might be with actually assuring that you hit the weakspot of the sprat. I got the achievement on my second kill after making sure I hit it’s head. It was looking right at me but the sneak attack still registered. It might have been a delayed pop, but you might have to swing at a few to assure you get it. You could potentially use another science weapon that’s easier to aim at but I did it with the hammer because it had the highest damage of all the science weapons I had at that point, even with my nonexistent melee skill.
Edit: Thanks to Reborn Insanity and YoDz who point out that there are sprat in the Rest-N-Go area right next door to where you pick up the hammer. If you happen to pick up the hammer after reading this you can attempt this about 20 feet from it. Just make sure to save before incase you don’t get it!
Edit 2: Credit to SpeleoFool for pointing out that Sneak Attacks require your sneak to be 20 or higher, so make sure your sneak is high enough!