Möbius strip

Möbius strip of 13 links

A Möbius strip is a surface that has only one side and one edge. It’s perhaps hard to imagine, but if you take a strip of paper, twist one end half a turn and glue it to the other end, then you have it. You can also build it out of Lego. This MOC was inspired by a MOC made by LegoOri at Rebrickable.com. After seeing that one, I wanted to make one completely out of Technic Lego and this is the result.

Notice that the image above has 13 links, i.e 13 sets of yellow bars and black plus gray hinges. It can still work with 10 links, but not less than 10. The more links one adds the longer the strip, which results in a ring that can lie down flat because the twist and the curves can be kept separate.

: 10 links

: 11 links

: 13 links

: 19 links

: 23 links

Notes on the design

The puzzle of the design is how to make one element. Originally, I had this design, that had separate parts for twisting and for bending. I was not really happy with it afterwards because it seemed clunky and because it was asymmetrical. With other attempts (see below) the twisting and turning hinges were also separated and the twisting hinges were kept in alignment with an axle. When one removes the axle (try to use less parts and see how a design can improve) however, suddenly the twisting hinges could also take care of the bending. I feared that they would not stay nicely aligned, but once I built a full ring that turned out not to be as bad as I thought. Somehow, the twist and turns keep them aligned, at least enough not to be disturbing. This is even true for the divisible strip that I made after this one.