So it wasn't the most productive way to spend my Friday I suppose, but last week I had some serious interest in Ofuro tubs. A few things caused it, some pictures from tumblr, references from Archer (animated TV series) and my general interest in Japanese culture.
Here are the two pictures in specific that got me going.
I looked at several things related to ofuro's and different ways I could go about building one, ranging from concrete to wood and finally settled on that this would have to be an outside thing for my tiny home and that a wooden one would be in the realm of things I could actually make.
Cedartubs.com had some interesting info and pictures that really helped me makes sense of everything.
This image really shows the look I would like to accomplish on this tub, but the real money shot was their technical shot (an export from sketchup) that showed the most important design piece, look at the image tell me if you see it?
If you noticed the beveled joint that makes it easy to do a radius bend with wood, you are very observant and have an engineers mind! I saw that and was stunned by how much easier that was than the complicated chamfering I was planning on doing to get the ellipses shape I favor.
In summary you need a source for Clear Western Red Cedar, a source for stainless steel or maybe copper bands (Cedar tubs calls out a specific grade of stainless) and a heat source. Clear is a designation of the grade of lumber you are buying, clear means it is free of knots (ie will hold water) so expect this to be fairly expensive lumber, the stainless or copper bands are to hold it together and have aesthetic value to enhance the look of the tub, and the heat source is really just supper nerdy to me, old school heat exchanger.
Take some time to understand what you are trying to build here so you understand that it is not a hot tub, it is not a bath tub, it is specifically for soaking away tension and traditionally has meditative value. It was also part of the social order of the household with the eldest and most respected using the tub first, followed by the next eldest and respected down. You shower and scrub yourself prior to entering the orfuro, and should not enter with any fabrics or detergents.