Citron watermelon (AKA Pie Melon, Tsamma, and Colorado Preserving Melon) is said to be useful for making pies, preserves, jam, pickles and such. It is not used for fresh eating, typically, and is hard all the way through even when ripe. The interior is supposed to be high in pectin. (I believe Tsamma sometimes refers to a similar kind of melon that may have different properties, FYI.)
I grew one plant that got 9+ melons (the Red-seeded type from Baker Creek). So, I'm wanting to know how to make them into pie, since it sounds fascinating, and I love pie. How do you make pie with the inside of the fruit? I know there are recipes for watermelon rind pie floating around there, and those may work with these rinds, too, but it's mostly the interior that I'm concerned about. If your response involves both the interior and the rind, that's fine.