- Find the folder you want to modify.
- CMD + I to open up the info window. Set this aside.
- Find the image you want to use.
- CMD + I to open up its info window. Click on the thumbnail then CMD + C to copy it.
- Go back to the first info window you opened. Click on that boring thumbnail.
- CMD + V to paste the new thumbnail image. PROTIP: this can work with any image. Transparent .png icons work the best.
- Bask in the glory of Nibbler waiting to gobble up your code.
*Tested only in 10.6.8 because I’m old school like that.