Has anyone tried doing the stained glass art projects?

I bought all the stuff and I am having a terrible time trying to cut the glass.  The glass cutter worked for the first few pieces now it is no longer cutting through the glass

This is another DIY I found on Pinterest. I just so happen to find the stained glass on clearance at Hobby Lobby so it was a win-win situation.

I already had an old bike that we took apart for this project. I love this idea but would really like to finish it lol.