Here's a link to the Photoshop action file -->
LINK, credits to streaker (creator) and nuka1195 (poster).
Here's a tutorial on how to use the actionfile with Photoshop, credits to J4ZZ -->
LINK. Ignore the link to the actionfile in the tutorial since its not working.
If you don't have photoshop, you can download the trial version at
Adobe.com. You'll have thirty days to use the app till the trial runs out, which should give you plenty of time to make all your icons.