Step 1
Lay out your stair design on a piece of graph paper with a pencil. Measure the area that you have to work with and the height that the stairs have to cover. Assuming that stairs need a maximum nine-inch rise for each step and a minimum ten-inch width for a tread, measuring the widest point on a pie-shaped stair, figure out the most sensible configuration for the space.
Step 2
Make templates for the pie-shaped stairs when you are building the staircase. You can make these out of stiff cardboard using a utility knife and fit them into place to be sure they fit. This is much easier than guessing with a piece of hardwood. Once you have the right shape and size, trace the template onto the material you are using for the stair and cut it out with a bandsaw or jigsaw.
Step 3
Attach the stairs to the risers either by nailing down through the face of the stair and into the riser or by attaching a cleat to the back of the riser and then screwing up through the cleat into the bottom of the pie-shaped step.