The first year that I participated in Andrea Zittel's High Desert Test Sites I made a Sauna.
I made it by covering a rock with wicker and plastic. I used the rock as a mold for the sauna's shape.
After removing the plastic from the rock, I reconstructed the shape by itself.
I hot-glued the plastic to the wicker.
The steam inside the sauna came from pouring water over hot rocks.
At night, the temperature in the desert drops significantly. Condensation covered the interior.