I have! it made me want to make my own neural voicebank.
UtaForum.net
Thehyami
IO+
I don't know much about making a machine learning voicebank, but i heard people using nnsvs to make ai vbs, look like they using utau vb as well!
Thehyami
Yea, I tried that, unfortunately there's only Japanese tutorial for the nnsvs. It can make other language too, but nobody is making it.