In China there is a phrase "everyone has his own advantages, that is to use the right size to measure the object. To measure more accurately, you need to use the right "posture" to use the ruler. Prepare the following materials and tools: a computer with internet access, CorelDRAW or other two-dimensional design software, HANS GS laser cutting machine and 2 to 3mm thickness of the sheet metal.
The process is as follows:

The first step: try to design a regular ruler yourself. For a ruler, the most important thing is to ensure the precision of the scale. The so-called scale is the unit of length marked on the ruler. The unit of length we usually use on a ruler is a metric unit of millimeters (mm) and a centimeter (CM).
In the CorelDRAW software, the most common ruler is to draw a rectangle figure first, and then draw the scale according to the millimeter. For example, we need to make a ruler with 20 centimeter scale and a centimeter scale, first pull out a rectangle about 21 centimeters long and 3 centimeters wide, and draw 21 intervals of 1 centimeters.
The second step: the ruler is processed by the laser cutting machine. In the laser cutting machine, processing ruler also has small tricks, scale, number, unit and so on can not be cut through, the laser cutting software to learn to learn to layered output. Taking LaserCAD software for example, we can set up a profile for the ruler layer, using cutting processing, scale, number, text and other units not to cut part of the set to another layer, the use of "carving" processing mode, or use the power "very small cut, just draw the outline never cut off, so you can make a ruler can be used.
The third step, you want a vernier caliper. In the open source world of the mak-er, many big cafes are making their own tools, and they are happy to share it.For example, a clever vernier caliper is made by laser cutting machine on the Internet. The attached ruler is made up of three pieces of wood chips. It is screwed together and nested on the outside of the main ruler. It can slide around the main ruler and the measurement accuracy can reach 0.05mm. The same accuracy of a vernier caliper, on the Internet to sell dozens or even hundreds of RMB.