These barrel style japanese tubs were built in the traditional way, without powertools or adhesives

Here are twin oval-barrel shaped hinoki tubs - 1520 x 670 x H710mm (ext. dimensions).
We used stainless steel bands to contain the water pressure. The client at first required copper bands, but it would be too weak so we proposed stainless braided wire which is solid and not too difficult to assemble. We reached the compromise with stainless steel bands: the look is very nice, but - boy - they had to be slowly hammered one by one from the bottom up and it took forever!

Another peculiarity of these tubs is that the bond for laminating vertical planks was replaced with 100% natural rice starch. See the blog for more details ->
http://www.bartokdesign.com/japan/0-blog_news/natural-tub-oregon-2.php