Mobius (Moebius) strip. Print vertical, needs support for base.

Final strip - I promise!
Different method of design (in MOI - Moment of Inspiration). The base is not flat so it is necessary to enable support from baseplate. The apex of the strip does not need support. Some of the photos show the item on the printing plate prior to any finishing.
I strongly recommend printing at 2x size.

Made in DiamondAge PLA on an Ultimaker 1.