Many apartments in Finland have saunas too, no matter how small :)
The compact 3-by-5-foot space is clad, walls to ceiling, in tongue-and-grove air-cured red cedar boards. A travertine-tile floor complements the wood interior.
4'x4' Home Sauna Kit | DIY Precut + Heater Package
The Boulder Sauna [design]—How to Build a Finnish Sauna: cedar, kits, heaters, building materials, tools, and health benefits
I want a little traditional outdoor sauna!
Small sauna - so CUTE!
CHEAP SAUNA KITS $1599 - DIY Indoor Sauna Kits