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 to the print head and most fans designs were a bit short or not offset correctly for my needs. This version allows this to be addressed as well as many other factors such as even selecting if you need a full circular or semicircular version, airflow angle, length, width, etc.
The posted stl files are setup for my environment so might not be optimal for other setups. I recommend that you click on the Customizer button and create your own version.