Take a look at this wonderful idea: herbs pot, turns into a BBQ in no time. Just remove the upper part, filled with green herbs and you can find the grill with the coals underneath. The hole near the bottom is for water drainage.
All you have to do is lift the herbs the reveal the grill. When you do not the BBQ any more, you can put it in the storage cabinet or put it again under the herbs.
Grow fresh herbs for the grill and keep your balcony and garden nice and clean.
http://www.doknow.org/bbq-and-herbs-pot-all-in-one#sigProGalleriacd7545dab8