Well, here's my first contribution. This fixture holds a violin bridge rigidly fixed at a certain position and angle, allowing you to fit the bridge to the top contours by dragging a piece of sandpaper under the bridge feet, instead of moving the bridge back and forth. The bridge stays fixed and the feet obtain the contour of the top precisely where the bridge will be located. The bridge position is set with the fixture held against the end of the fingerboard by turning the bow adjuster knob. You do have to be careful that the back of your sandpaper and the violin top is perfectly clean to avoid leaving scratches in the finish. You can tape some wax paper over the top if the finish is pristine, but on the old fiddles I usually work on the backside of a piece of sandpaper could only help.