First step was to make a panel template 2.5" wide at the top (0.25" seam allowance at each side) and 3.5" wide at the base with a depth of about 16" to allow for the fold over waist.
Then I cut out 12 panels from my stash - 2 more than needed for the 20" waist so the final item would have some gathering.
Then I arranged them into an aesthetically pleasing sequence and began sewing the long edges together.
Which produced a quarter doughnut shaped effect.
Samuel and I were multitasking on reading homework for the above steps...
I could have folded over the lower hem but decided to bind it with the selvage edge of one of the fabrics had used to keep as much length as possible.
Starting to look like an actual skirt now...
Final step was to fold over the top hem by about an inch to make a place for the elastic to go, add the elastic and sew the last long side hem together, trapping the elastic in the final hem. Here it is all finished. Hope the Birthday Girl will like it!