Sometimes I just want to change a default icon (e.g. for a folder) in OSX. So where to do this? First you need a source image to copy. These day just about every image you can preview can be used, as well as other Application or Document icons. It wasn’t always so.

Step 1: Choose a Boring Folder That Needs a New Icon

Say for instance we want to use the Blender icon for the folder it occupies in our Applications folder. The default is the boring blue folder.

Step 2: Find the Image You Would Like to Use Instead

I enter the Blender folder, select the actual Application and choose Command – I (Get Info) to get the Info window:

Step 3: Select and Copy the Small Icon Upper Left

The trick is now to select the small upper icon in the upper left and Command – C (Copy) it. It's actually a detailed icon.

Step 4: Change the Folder Icon

Now you select Command - I (Get Info) for the icon you want to change. Again, select the upper left small icon so it gets a selection border.

Step 5: Paste the Copied Image Over It

Command - V (Paste) now replaces the boring icon with the one of your choice.

Step 6: Voila

...a folder with a nice icon!