Fireflies Etching

There is this girl that I am in love with and am going to soon ask out, whose birthday is coming up. She loves the song Fireflies by Owl City, and I wanted to do a glass etching project that incorporated the song. What I wanted to do was on one side of the glass - cup or vase, Etch a lyric to the song, and on the other side etch some drawing of fireflies or something relating to the song.
I would like to do this with a high speed rotary tool, as opposed to etching cream. I have experience with precision with the device, and i have also done wood burning. How difficult for me would this be to do?
Also, could someone suggest an image to etch into the glass?
All Help Is Greatly Appreciated
~Matt