Rope tied around a sphere.
I got a hold of this large steel bearing. Then I tied a rope around it and my daughter untied it. Over and over! Eventually she fell asleep, and this is the knot that stuck.
Oh, and then I made a 3D model of it and put some stuff inside and whatnot. All done in the Gimp and Blender.
A sealed glass flask, containing fluids of unknown origins. Why don't they mix? Why is the green liquid so much denser than the orange? Are they metals? Who tied that gorgeous knot?
The glas flask and ropework, without the fluid. Who wants fluid in their flask anyhow?
You can see the ropework pretty well here. I tried to make it as close as I could to the original, but after a while I grew tired of tweaking bends and knots and called it good enough.
The real steel sphere knot
The real steel sphere knot, this time in daylight