IconBuilder, as its name suggests, is a program for creating Mac and Win icons in standard and unique sizes. It comes as a plug-in that can be used with Adobe Photoshop. With this, it is possible to create icons of any sizeup to 1024 x 1024 pixels, to build icons for an entire project in a single filter pass, to save icons in different file formats simultaneously, to adjust alpha thresholds for 8-bit resources, to import the existing icons, etc.
