Fully customizable parametric fan duct for 3d printers

This is my version of the popular various circular fan designs available. This version is based on the design by Arjjck , link: https://www.thingiverse.com/thing:1620630. The side tab design idea is from Asasiel, link: https://www.thingiverse.com/thing:2186878.
I wrote it from scratch using Openscad and as such offers full control of most aspects needed for a correct fit on Anet A8's or similar printers using the standard fan duct arrangement. In my case I tend to have my nozzle fairly high