I took on the remodel of our home in New Orleans which included a second story addition. After looking at all kinds of spiral staircases, the kits ranged from super rickety to super expensive, so I decided to take on figuring it out myself. The house was originally built in the mid 1800's and as we took out some of the walls we ended up having a stock pile of 200 year old barge boards which I ultimately used in the construction of the stairs. I first made a template for the treads out of 1/4" ply ( and yes there were a couple versions). I biscuit joined the barge board together, then glued it on top of the template. I used a jigsaw to cut along the template, and hole saw to cut a snug center hole. 2" steel pipe is at the center with 2 1/2 pvc (which fits perfectly overtop) as the initial riser spacing. New 2x8's as the risers, 2x2's as the structure for stair rails with salvaged wood as accents and tops, and lots and lots of screws. After sanding and finishing and touchups, the final touch was a geometrical mural that winds up the wall with the stairs.