Many of my images have originated out of my experiments with the SolidWorks mechanical design software. This is definitely one of those. In the 2005 release they added the functionality to be able to rotate profiles along sweep paths. Although, you are limited to an integral number of revolutions for a closed sweep profile, so there is still no simple way to generate a M�bius strip, it is still a really slick way of making a multiple strand cord shape.
These knots are based on a Carrick bend, also known as a sailor's knot or as an anchor bend, or even as a Josephine knot in macram�. Normally fairly easy to untie, these virtual knots are formed with closed loops of cord, so, were they not virtual, they would be very difficult to loosen. You would probably need to resort to undoing the tedious splicing that is required during assembly to get it to all hang together.