Though they may sound like a form of gymnastics the Parametric Rings are simply ordinary loops you may print in colour.You can change settings in the Parametric_Rings OpenSCAD file to set the diameter of the rings, and to choose from some optional extra supports. You may need to use the supports when printing large diameter rings as they tend to warp and/or lift from the bed.You can export single rings to be printed in the suggested colours or you can export a full set and print it in a single colour.A short video of one possible way of assembling the rings can be viewed at: http://yuleblinker.com/parametric-rings/The ideal colours to use can all be found as part of the Rainbow Fun Pack available from http://www.faberdashery.co.uk/products-page/print-materials/rainbow-fun-pack/. (I am not associated with Faberdashery at all but often use their plastics).The suggested colours to use are: Electric Blue, Mellow Yellow, Classic Black, Village Green and Fire Truck Red.You can print a single ring at about 60mm diameter easily with each colour from the Rainbow Fun Pack. Creating the ring models:Printing the rings If you choose to print large rings (anything above about 50mm) then you may find it a challenge to get them to stick to the printer bed. The stresses set up as the plastic cools tends to make the rings warp and lift off the bed - experiment with the different support structures included in the OpenSCAD file. I found the 'mouse-ears' worked well for 70mm rings. The first and second picture shows a blue ring with 'mouse-ear' supports. In the second picture the support material is being removed.If you need some help figuring out how the rings can be assembled then look at the OpenSCAD file with the Linked_Rings option uncommented and hit F5.