I have not seen this since it first came out, so I can not offer actual ideas, but it might be helpful to Google 'Rent' and visit the web sites for the production and/or the movie...if nothing else, here's a bump...
I have seen this show quite a lot and one of the themes involved is from the main song "Seasons of Love". On how do you measure a year in the life of a person. Look up the lyrics for this song and you may be able to take some of the images they sing about and put that on the cake with maybe clocks around the side showing different times. Hope this helps.
you could replicate the DVD cover here is a link. I would do it without the people though
http://www.sonypictures.com/homevideo/rent/index.html
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