For those looking to build a home ice-bath system, that uses water instead of ice, here is an option that might be a good fit for you.
I purchased a chest freezer (Kenmore) perfect for 1 person up to about 6’6 and 250lbs+
Dimensions: 14.8 cubic feet
Internal measurements: 4 feet long – 3ft deep – 1 foot 8 inches wide
Leaking: I sealed all the internal edges with silicone – to prevent leaks
Base: I used wooden planks to prop up one end of the freezer to allow drainage on the other end
Drainage Screw and Tube: If your tub is outside it can drain directly otherwise you will need to get a hose to direct the drainage. I added a small hose since my tub is in my garage, with a 1/8th inch male adapter to drain.
Fill the tub about halfway with water.
I added 2lbs of Epsom salt and a few drops of food grade hydrogen peroxide 12% to help keep the water clean.
Timer system: I purchase a standard light timer which enables me to keep my tub at my desired temperature (between 35-38 degrees).
I ran the timer for two days to get it to proper temperature and now I just set the timer to turn on the cooling for 2 hours a night.
I have 3 gauges: a standard pool gauge, an aquarium thermometer (cheap and inaccurate), and a laser surface thermometer. You really only need one I was just testing the accuracy of a few different options.
I empty out my tub every two-three weeks depending on how frequently I use it. Then I thoroughly clean and disinfect the inside and replace with fresh water, along with the epsom salts and hyrdrogen peroxide again.
A pool skimmer works well to take out any misc dirt or items that end up in the tub. We also installed an outdoor shower and require everyone to rinse off after coming out of the sauna before getting into the ice bath. This helps keep it somewhat clean.
Always unplug your timer prior to using the tub. Electrocution is not the type of stress we are trying to adapt to.