Anything I can do with an old bird cage about 2' tall x 2 1/2' wise?

Put it outside in your garden with assorted plants.

I have used one for an indoor decoration.....put a big pillar candle in the center and surround it with greenery, flowers, or grapes. I have even put a live plant in the cage and it does very well......was a vine and it wove itself around the cage. At Christmas time a red candle with ponsettias, christmas balls and greenery looks very festive. You can even add those miniature lights. My grandson had fun one Christmas putting it all together for me.

I would put it on a pedestal in the garden and make a fairy garden out of it.

This is the search I used and they are really beautiful.

https://www.google.com/search?q=fairy+garden&rlz=1C1CHFX_enUS560US560&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjF27P5wejTAhUI7oMKHTgvCCYQ_AUICigB&biw=1600&bih=770#tbm=isch&q=fairy+garden+with+bird+cage

Spray paint it a bright color. Put some succulents in little color pots and hang them up with fishing line from the top and let them hang at all different levels within the cage.