Draw anything. An algorithm searches 1,730 real stars for the place your shape can be found.
When you finish drawing, every pair of the ~900 brightest stars, 2.5° to 25° apart, is tried as the two ends of your shape, and the rest of its corners are looked for among all 1,730.
Star positions and magnitudes are from the Yale Bright Star Catalogue, including every star of visual magnitude 5.05 or brighter (long-period variables such as Mira at their catalog magnitude, near their brightest; the recurrent nova T Coronae Borealis, cataloged in outburst, is left out). Positions are J2000. The chart is drawn as the sky appears overhead: north up, east to the left. Your sketch is simplified to its salient corners, then tested against candidate star pairs under every rotation, scale and reflection. The match score falls as the stars stray from your corners.