AMS Piano Tools
Weighing only a few ounces, the Tautline Tool is an ideal jig for simulating string height in the field (works great on your workbench as well). Assembly is quick. Just use the piano's action mount screws to hold the Tautline's flexible end-posts in place. Use it on one or more sections. Height is easily set by moving the attached pre-looped string on the end-post and bending the flexible post until the string is "taut".