Knot
thingiverse
I'm not exactly sure what you'd do with it, but we're making a hollow one to cast with silicone as a dog chew toy, because our puppy prefers hands over all of his remaining chew toys (after destroying several already). I also threw in the solidworks file if anyone is interested.
Download Model from thingiverse
With this file you will be able to print Knot with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Knot.