Here is my new TMS system which is made from a 75 litre Husky storage bin.
All of the black 1/2" HDPE components were machine by me utilizing a drill press and a router table.
It will hold an easy 150-200 meters of tether, hand cranked and a place to mount the ROV.
The ROV actually bolts to the lid to prevent it from slipping.
Super simple way of keeping your tether under control.
Also a nice shot of my ROV and custom made controller.