Wood turning calipers
Cut out 2 of the above images with a scroll/band/jig saw and rivet together or clamp with an M6 nylon screw and wingnut to produce a handy set of calipers for wood turning and other uses. Additional small bits of the same material (3mm ply suggested) are glued onto the opposing sides of each pair of jaws to provide an overlapping closure point (see picture).
The calipers are very handy for sizing spindle or tennon diameters and also for gauging the wall thickness of bowls up to approx 250mm or 10" diameter.
Other shapes can also be made in the same manner, this last variation being particularly useful for accurately gauging an even wider range of sizes. Simply right click the following image and select "save as" then print it out onto a single sheet of A4 paper to copy the design.