Finger operated L/H 3 speed changer needed

[Gillstay]

Hi. doing a bike for a chap and he has a dodgy thumb, so needs a changer for the front chain wheels which preferably is operated by fingers or is very easy on the thumb.

Any ideas gratefully received.

 

[Ming the Merciless]

Straight handlebars?

 

[Ajax Bay]

STI only needs fingers (unless old Sora or Campagnolo).
Flat bars - go for twist grip.