A bridge lift or bridge jack can be very useful for lifting the stings momentarily for making adjustments to a bridge on an instrument that is already setup.
I was disappointed with the cost of commercially available jacks so I made this one on my own. Two short pieces of coat hanger wire act as guides on each side. The lifting screw sits on the head of a filled down screw in the lower portion to prevent it from sinking into the wood. Make sure the tensioning knob is small enough to pass between the D & A strings when placing the bridge jack next to the bridge, otherwise you would have to remove the screw each time!
Note: obviously a bridge jack is not useful in setting a sound post. The setter and inspection mirror are sitting next to the bridge jack because they live in the same box 🙂