For a customer order, I was to insert an intermediate layer within a flower vase at a certain height. Due to the height and shape of the vase, which tapered downwards, it was practically impossible for me to determine the inner diameter at the defined point.
What I needed was an inside caliper. Because of the delivery times I decided to construct something myself.

I have designed two versions in different lengths. A slightly smaller and more manageable version with a leg length of 120 mm and a longer version with a leg length of 180 mm. Both have a scale with which the measured value can be read quickly and easily. In the smaller gauge, each point corresponds to 1 cm and in the larger version to 2 cm. Both devices are designed in such a way that one-hand operation is also possible. The opening angle can be fixed by means of the small locking screw.