I designed a 3D printable gauge/ruler that can be used to measure the string action on a guitar or ukulele. It features measurements in both millimeters and fractions of an inch. It can be optionally printed in two colours (does not require a multi-colour capable printer). Or print in single colour and use a sharpie to fill the depressions.
I designed and printed a wall mount for Ukulele with narrow ledges on the right and the left, to store a tuner and/or a capo. The mount works well with my Tenor and Soprano ukuleles.