Toroidal Blade For Desk Fan by Dwarfalicious on Thingiverse: https://www.thingiverse.com/thing:6002251

Summary:
This is a 4" (10.16 cm) diameter blade. This was drawn for a HomePointe High Velocity Personal Fan.This toroidal design was made using ellipses rather than circular shaped bladesIt is my opinion that this blade is much quieter than the original stamped sheet metal blade.The "5_blade" and the "Thick" files circulate the most air.The toroidal shape works well for circulating air in an area but not for directing it in a strait line. This works well for keeping your whole body cool rather than directing air at one part of your body.