This is a simple mod but a must have in survival servers.
Hook: hit on a edge to climb up.
Upgraded hook: use with double hight
Rope: place on a edge to climb, or throw it.
Locked rope: only you can take it, or throw it.
Slingshot: throw junk far away and hurt your enemies place it to change side to use
Mouth breather assembly: use outside water/vaccum to refill with air, use in water/vaccum to refill your breath (max 10 times))
Pchest: portable chest, the stuff is stored inside the chest/tool, and not in a ghost inventory.