Plastic knuckles with some weight.

thingiverse

Unable to access the initial DXF file, I resorted to taking a screenshot for reference. The captured image displays the design's progression. The tube dimensions cater specifically to a roll of US pennies. Rest assured, this creation won't trigger a metal detector. Attach it with a leather thong, and you have yourself an eye-catching necklace. I opted for PLA during my 3D printing process. So go ahead, print your own, and steer clear of trouble!