Create A Simple Design
Create a PNG with your design using Windows Paint, Sketch, or Figma. The suggested resolution is 512x512 with a transparent background.
![](https://tetrapyloctomy.org/content/images/2023/12/CleanShot-2023-12-28-at-18.00.58@2x.png)
Generate the ICO Image With Retro Encabulator
Use an updated version of handy Linux edition of Rockwell Retro Encabulator, a.k.a. ImageMagick's convert utility to convert PNG into ICO file:
convert \
favicon.png \
-define icon:auto-resize=256,128,64,48,32,24,16 \
favicon.ico
Profit
Profit.