Made out of acrylic. Very simple but works great.
Air is supplied by a aquarium pump. Heat by a modified aquarium heater. Mine had a little plastic piece limiting the temperature, easy to cut of. Now it heats the bath to the right temperature.
The cutter pictured works great for acrylic. Mark on both sides, then break over a well defined edge.
Heater mount, very simple to do...
Glue the whole thing together with special glue for acrylic, amazing stuff.
Cutting the parts first. Those pictured are for the base, secondary containment. Really a good idea to have...
Air bubbles: porous hose never lasted very ling in the past. Hypodermic stainless steel tubing dies a better job. First mark with a center punch, then drill holes in it. Very small ones of course. Plan on breaking a bit or two.
Ends are squeezed tight and rolled up a bit to seal them on one side.
After that both tubes are mounted on a acrylic base with silicon to ensure proper positioning in the tank.
Done and ready to go. Make sure the glue is fully cured and test for leaks with water before filling in the acid...