Not that I know of (answer to both questions).hans wrote:Are any bansuris made which have a thumb hole for a better vented natural fourth (Ma)?
(Tonic 'Sa' being L1, L2, L3 closed [and thumb hole closed if there is one])
Are there any master players using a thumb hole?
Probability of it also low, very low IMO because
1. aesthetically not desirable (in the tradition)
2. technically frowned upon (talking about "masters" by which I take it you mean "of classical")
3. would interfere with current left thumb placement in all of the SEVERAL grip types for large bansuri.
(see links in earlier posts here)