Coconut drinking cups?

hi im making some tail cups from hollowed coconut shells ive got them all sanded i just need a food/drink safe varnish/sealant to waterproof them as i left some water in then to check for leak an the wer seems to seep through the shell i was thinking of painting the inside so maybe a safe clear varnish i would like a gloss finish on the inside aany ideas thanks also i need to have 10 made by 27th march 2010 so time is tight many thanks