Thước đo góc ergonomic (Ergonomic quadrant)

This instrument helps for computer users to create a confortable work enviroment. 

I was looking for a description of the optimal positions for an ideal computer workstation. 
I found many, and some of them contradicted the others, but what they had in common was that they gave the position of the user and the monitor/keyboard in degrees. So I made a simple tool to measure this angle.

Print: 

You need 1 of each model I uploaded, print them out following the instructions below:

• The "plumb" consists of two parts: a body and a tip. The body can be printed without support, the tip requires minimal support
• The meter body should be divided into layers and the filament should be changed at least once to ensure that the scale is clearly visible.
• no other special adjustment is required

Assembly:

Apart from the printed parts, you only need a 20-25 cm string/thread. 
I even drilled through the holes slightly to make it easier for the thread to go in, but that may not be necessary.
You just push the thread through the hole in the top of the pendant and knot it. You press the two parts of the plumb together.
You do the same with the hole in the middle of the gauge. 

The device is ready to use. 

It should be held in the right hand, making sure that the scale is pointing downwards and approximately vertical. The thread will then just touch the edge below the scale. Hold the instrument with your hand so that the thread is not touching.

Look into the smaller hole and locate a top and a bottom point on the monitor (I have attached a picture for the test with different points). Once you have the points aimed, you have to wait for the plumb to come to rest and either have someone read the angle value or fix the thread with your left hand and then read it.

Hope it helps some people have a healthier/ergonomic workplace.