1) Measure out 30 yards/27.5 meters of the yarn of your choice.
2) Use your knowledge of increases, decreases, stitch variations, short rows, long rows, and all the stitches and motifs you care to include, and make your own motif.
3) You may work in any direction you choose -- in the round, linearly, standing on your head...
My first effort didn't quite finish within the parameters:
Improv A Long Motif
5.0 mm (H) used about 30 yds of Red Heart SS in Ocean.Ocean
My next and favorite is the Pockets and Pillows Motif used dk Knit picks Merino Style and a F hook/3.75mm
My fourth one, Caribbean Window, used a G/4mm and Knit Picks Swish Worsted
This was great design calisthenics!