Once you have your icon looking the way you want it, go ahead and save the file. It’s actually an interesting read no matter what (at least if you’re interested in icons and such). If you’re creating an application icon, I highly recommend following Apple’s OS X Human Interface Guidelines when creating your icons. This image will now have the same size and transparency as the original, and can now be loaded into its own layer in any graphics editing program that supports them (which should be most of them).
#CUSTOM FOLDER DESIGNER FREE FOR MAC MAC#
I’ve been making my own Mac icons for folders, applications, and a myriad of other uses for well over 20 years now.