Violin chart in D3
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Any ideas on where to even begin with making a violin chart using d3?  Does it exist already?

I've looked around and have figured out how to do it using ggplot2 and was hoping there'd be a ready-made example that I could learn from but haven't found one yet.  

I suppose I could do a really painful process of making various size bars on top of each other, or taking a distribution, rotating it and mirroring it.  But surely there's a better way.