My partner and I are working an entrepreneurial project for school, and we decided to make a sort of edible water bottle.  We decided we would make it out of bread, which we would cover in some solution and leave to dry to make it hard and waterproof.  We considered using honey, but it would be too sticky, sweet, and expensive.  Is there any good solution that will make this bread waterproof and hard easily? Something that is cheap and not bad-tasting?  also, if you think this question should be posted on a different stackexchange site, please tell me.  Thanks. 
I can think of a few things, but I'm not sure how well they'd work for water bottles, specifically, as I don't know what the temperature of the liquid is how long it needs to function as a container, and how long it needs to be on the shelf before use.  (and what liquid you're using, so it doesn't make things taste really foul).  If we're just using water, I'd be inclined to use:   Nut butters : (eg, peanut butter)  The high oil content will repel water.  Of course, if it's being held for long times, you'll have issues with rancidity.  And it doesn't really harden up at room temperature. Chocolate : so long as it's not a hot liquid, it'll resist water for quite a while.  This is one case where 'coating chocolate' may be better than real chocolate as it's got a higher melting point.   I personally wouldn't use honey as it's water-soluble, and will start disolving into even a cold liquid. 