Next project? A spiffy (and possibly insulated) ofuro, a Japanese soaking tub.
That, or an entire outdoor water/entertainment center with a wood-fired hit tub, steam room, pizza oven (why not?!) … you get the idea! And, as the funny DIY link below says, become “psychologically dependent on it”!
Suggestions are welcome regarding which asphyxiating chemical to use to waterproof it … fiberglass, marine paint, epoxy, or something else.