This is a pen holder cup with the sides made up of double helixes. It prints best with supports, but breakaway supports aren't really an option. They would have to be wash away supports.
It's customizable, you can change the height and diameter and the number of double helixes to use is calculated automatically.
You can print the whole thing in one STL, or get separate STLs for the top rim and half of the helixes, and the bottom plate and the other half of the helixes if you have a dual extruder with multiple colors. The bottom plate is 4mm high, so if you're using multiple colors place both STLs on the build plate, then move the colorB STL up in the z-axis 4mm.
Added STL file for a 110mm (height) x 35mm (radius) holder.
Updated design with optional supporting spirals for better printing.