Yeah, there is a lot of Crepe Myrtle down here in Fla.
Let us know how the bow build goes. It is a very hard wood! I would imagine the grain is not for a beginner!
The arrows should pretty strong, but I would imagine they would be heavy. Let us know how it goes with both projects. An aside note, the leaves are supposed to be good for diabetics, when made into a tea. I have tried it, and it is not unpalatable, but you could mix it with regular tea. It is an Indian(India) herbal remedy, called Banaba, or something like that. There are a couple of species of Crepe Myrtle, the ones in India, are huge, like the Giant Sequoias.
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Keep us updated.
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Wayne