Meet DRIVERS, the handy tool for Blender! It makes making shape key drivers really easy.
effortlessly link drivers to shape keys with just a few clicks.
Just click and go!
It's like magic for your animations, making them super cool and fun.
Select your Shape key object, and press Picker button in the Drivers panel, and you can see all your shape keys there,
while working with armatures this becomes very handy as you do not need to select object again and again to check shapekeys
Add Object or Bones as Drivers
add any object or Bones as driver with few clicks, select your object set transformation value, adjust min and max values, and press the assign button located besides shape keys.