How to get a model of only the index finger?

In my app, I would like to enter a "selection mode" by pressing where you can raycast from your finger to an object and select points on the object. 

My issue is that it's annoying to select with your index finger on the standard hand because it's very easy to accidentally touch a trigger and contort the hand model and screw up the raycast direction.

My question is, how can I get only the model of the normal, extended index finger? I want to press a button, enter "selection mode", and then have a static model of the index finger that can't be closed or contorted in any way.