I love this product I have found http://containergardening.about.com/od/reviews/gr/PotPads.htm
It’s rubber feet for pots and containers.
I was recently overhauling some troughs planted on a deck 3 years ago – underneath some of the troughs it was very wet and some white mould was growing there. I decided they could do with raising up a little to allow some air flow and help the deck to dry out. Browsing on the internet I found this site with the perfect solution: pot pads. The only downside is they do not have a stockist in the UK, and I had to have them delivered from the USA. However shipping was not exhorbitant and they arrived quickly. You cannot see the pads once installed, and the troughs look good slightly ‘floating’, as you can see below. A definite thumbs up.