I'm aware of hidden emoticons of skype, but I'd like to create my own emoticon.
Is that possible to do? If so, how can I do that? Is there any tool for that?
This is pretty weak. Mac users are allowed to modify their Skype emoticons.
Right click the Skype application and choose "Package Contents." Go to "Resources/Emoticons."
Add your picture to the animated emoticon set folder or the emoticon set folder. In the animated folder you must save the file as a .gif, in the emoticon folder as .png.
emoticons.plist with the property editor.
Add an entry
fpr for your smiley. Name the object as the file name with .gif in the animated folder and .png in the regular folder. Add the strings that you want to appear as the smiley and as the name equivalents.
Create a boolean and name it hidden. If you have difficulty with the programming aspect you can check the entries of the other smileys for examples.
Save and relaunch Skype.