Linked torus

Linked torus

Two identical tori that are mutually and symmetrically linked.

These things have no immediate practical uses (that I know of), but I am interested in their geometry and kinematics. I used them as an exercise to figure out Tinkercad basics (navigation, sizing, alignment), to experiment with minimum practical clearances and printer/surface quality/errors, and as a shape element that can be used in future projects (for example, as the core element of a simple universal joint).

Clearances:

The three models have a difference of minimum clearance between the two tori. If printed at the original scale (each torus radius-to-center-of-tube = 6mm) the centered nominal clearance between tori is:
* no clearance: 0 mm (rigid, the two tori are fused at near-tangential contact)
* low clearance: .1 mm
* high clearance: .4 mm

Scaling the STL model will increase or decrease the clearance, proportional to the scaling factor.

For the low clearance (.1 mm, nominal) models t