A bracelet formed by a toroidal knot and it's mirror.
Inner Diameter = 67 mm [~ 2.6'']
Outer Diameter = 87 mm [~ 3.4'']
Height = 20 mm [~ 0.8'']
The main shape is that of a revolved ellipse (elliptical torus) on top of which, the "knot" winds 13 times around the main torus axis by apparently 12 "strands" (which in fact is only one).
To reinforce the structure, the same toroidal knot was "wound" in the oposite direction, hence the criss-cross pattern.
This is the first model I make without using any CAD software, but just plain mathematic modelling using Wolfram Mathematica ®.