This is a hollow tube infinity symbol - just for fun. For an added twist (pun intended) I dropped a small (8mm) ball bearing into the print about half-way through (I should have used a slightly smaller bearing as the one I used tends to get stuck).
You can see in the photos where I added the ball bearing.
The OnShape 3D CAD file for this is located at the link below:
https://cad.onshape.com/documents/6e5cf74be55921b7737ad5e5
/w/dedd6ec1ac1e3045d218dec9/e/5d60206ab5ce9a2085a9c6dc
I printed in clear PLA. Lay the print flat on part of one loop - there is very little contact with the build plate due to all of the twists in the loop.
I used the "supports on build plate only", plus I added a small custom support where the loops cross over.
The inifinity-test.stl file is a short segment of loop you can use for quick printing tests, as well as to get an idea of the inner diameter of the tube.
You can use the provided print files, but there is probably plenty of room for improvement in the print settings.
The author marked this model as their own original creation.