This structure is meant to be printed without supports. There are many tests designed for a 3D printer to print without supports in a straight line, but not all designs have straight lines. This Test is designed to test your printer's ability to print a curve without any support. This print is probably best monitored so that you can stop it whenever you reach the failing point. I highly doubt any printer will be able to print all the way to the top without failing. There are now two files. One has rings at 2mm thickness. The other has rings at 0.5mm thickness. Tinkercad. Printed Makerbot Replicator 2 no supports.