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.