it is not very functional as the bottles get stuck very easier, i just use flat rectangles and shape them. also decrease the friction on the parts that the water bottle goes down. if you are not advanced i would recommend push or pull vending machine because they are much easier (there's one on my page).
very nice man! sorry but if you dont mind can you please help with this truck http://www.algodoo.com/algobox/details.php?id=258028 it would be deeply apprectiated!