1. Find four primary stones.
2. Place the stones in the North, South, East, and West directions.
3. Gather 16-30 smaller stones.
4. Place those stones in a circle connecting the four primary stones together.
5. Gather sage, a vessel, matches, and a large feather together.
6. Light the sage and when it smolders and creates smoke, wave the feather over the sage in the direction of the sacred circle of stones. Do this for 2-3 minutes.
7. Step into the cleansed space to meditate, pray, or any other activity you wish.
Some people like to keep the stones they've gathered and bring them along when they travel. I encourage that but caution them not to have overweight luggage. I suggest they travel with much smaller stones as it is intent, not size that matters.
Finally, you can create a Temenos anywhere, inside or outside as long as the steps are followed.