There are actually many things you can do. First, how big is the cabinet, need length,depth and high measurements.
I just converted over an old china cabinet for a handicapable dragon, made it into a castle for him.
Many folks check yard sales or craig's list local to them for stand alone steros, you know the kind made in the 1970's with a turn table. These are easy to convert into a single story enclosure.
You can also build from scratch an enclosure and custom it to your and the dragons taste from this site:
http://www.freewebs.com/crossfireenclosures/
I am making a stacked duel set of enclosures for my two 9 1/2 week olds, similar to this instructions.
You can also check out the enclosures threads to get ideas.
I hope this helps you out !
Janie.