Sorry Marco, better not...

Best regards
Stefan

OK. No problem.

Bye.

That is the one I half remembered, only 5 years ago!
Time to try again...
As far as I know, there is not a .3dm available.
- Brian

The front view and the left view are symmetrical.

Hi All,

Thanks for the leads cant believe the historical trail needles in a haystack falling in the same pile - MOI a great forum with a diverse range talents!

Will digest posts contained.

Best regards

IMHO, the "yin-yang" is a seifert minimal surface on a trefoil knot.
Using the flat crossing knot diagram of the trefoil knot, showing two holes, the "braid" type,
there is a procedure to make a seifert surface by replacing the crossings by bands rotated 90 degrees.
Unrotating the central band orients the two holes to 90 degrees, and the flat surface becomes 3D.

- Brian