The pair of earrings that is similar to a DNA helix was created with the help of Henry's fascinating tutorial, "Creating Springs in TurboCAD", found here: http://forums.turbocad.com/index.php/topic,15862.0.html
. They are polished brass, made at Shapeways. Their technique is to print in wax and use a traditional Cast Pour, the same as high quality jewelry is made. A drawback is noticeable where one of the helix segments is wider than the others and one is narrower. That was not intentional; it was a byproduct of the wax being deformed at some stage.
There is an intentional deformation; I created everything with a circular profile, then compressed the longest dimension to give an elliptical shape to the strands. My first attempts were to start with an Ellipse, but joining the main body to the section that spiraled in towards the center proved problematic, so I determined the desired 'squash ratio' and altered my design from there.
The second pair shows the repeated use of the Arc - Tangent to... and Circle - Tangent to... functions, with a Rail Sweep of a rounded rectangle on each resulting Polyline providing the 3D object.
TC Pro Platinum 2017, 2016 & 2015 (all with LightWorks) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1