I made a carved watermelon bowl for a beach themed party I went to recently. I found some simple hibiscus flower clip art online to try and it worked up pretty good.
I did the design before I carved the melon so it was easier to work with and I could wash it down after I was done and get rid of the marker lines. it tends to dry up depending on how long you work on it (took me 2 hours start to finish) so washing it helped to let it soak up some moisture.
I cut the top off and scooped out the inside, rinsed it out, patted the outside dry and wrapped it in plastic to set in the fridge until later that night, then I filled it with fruit right before I left.
it was so easy to do I would definitely carve one again if I find the time!