From GT New Horizons
A light green Y-shaped slingshot with even lighter green string.

The Slimesling is a slingshot shaped utility tool for increased player mobility from Tinker's Construct. When held and left-click is sustained, the Slimesling shakes and charges up. When released it will launch the player up to twenty blocks in the air at an opposite vector to wherever they're looking both horizontally and vertically, depending on how long the Slimesling was charged. Aiming straight down at the block below the player's feet will send them straight up into the air. The Slimesling is best combined with fall damage negation such as the Piston Boots or Slime Boots and the Hang Glider for early game travel. It can be used to jump over short barriers or Canyon cliffs without needing ladders or a staircase. The Slimesling does not work if there is no block directly below the player's cursor when released; it cannot be used in mid-air.

Prior to version 2.5.0 it was uncraftable due to uncapped movement speed/distance that could cause server crashes. Players familiar with the Slimesling from other versions of Tinker's Construct will find the GTNH version far more controllable and limited. The Congealed Blue Slime blocks needed to craft one involves finding a Slime Island or otherwise growing Slimy Saplings and LV tier machinery.

While it cannot be enchanted directly in an Enchanting Table, the Slimesling will accept Unbreaking from a book and Anvil. It can be repaired with the Thaumic Restorer or Dragon Essence Altar and has a maximum durability of one hundred uses.