Originally, the fingers used 4-40 bolts for all of the holes, but since the metric bolts fit better, I swapped all of the bolts out.
I needed to bevel the inside holes on the parts in order for the beveled bolts to sit flush with the surface of the acrylic. To do this, I used a drill press with a drill bit the same size as the beveled heads. I also cut the bolts down a bit to prevent them from catching between the fingers.
CUT THE BOLTS CAREFULLY. This can cause trouble if done without safety glasses and gloves. Also remember to put on the regular nuts before cutting the bolts and take them off afterwards. This will keep the threading from deforming when you put the lock nuts on.
For putting the finger together:
Put the beveled bolts on first.
Then the other bolts in any order.
Each bolt also gets its own washer and lock nut