For creating ico file out of multiple png files one of the best tools is png2ico.
Following are different ways to download and install png2ico
Installing from Source
download latest png2ico source from here and run following commands:
tar xzvf png2ico-src-2002-12-08.tar.gz
cd ./png2ico-src-2002-12-08
./configure
make
sudo make install
OSX
OSX users have the png2ico package directly available trough port. you need to run following command
sudo port install png2ico
Command
After installing png2ico you can run following command to generate required ico file
png2ico myicon.ico icon_16x16.png icon_32x32.png icon_64x64.png icon_128x128.png
- Note that the ico file has limitation that the maximum size supported is height < 256 pixels and width < 256 pixels.