One of the most underrated lab tools is the resistor substitution box.
In reality, this tool is very useful for experimenting with circuits when there is a need to test them with several different values of one or more resistors. Rather than replacing several times the resistor, a simpler approach is to connect a Resistor Substitution Box and use that to provide to the circuit various values of resistors.
There are several commercially available devices like this, ranging from a few tens of US dollars to several hundreds, depending on their capabilities. But, if you are a newbie and would like to try to build a tool like this, I strongly suggest you to do it. It is a very simple project to start with, and you will end up with something useful to add to your beginner lab.
To help you on that, I have provided all the needed files to build the box for the instrument, like the one in the picture above, and the schematic of the internal circuit.
You can find the zip file here: resistor_box.
You can also refer to the corresponding video I published on YouTube, where you can find instructions on how to build the device: YouTube video.
I hope you will enjoy making the Resistor Substitution Box, and use it in several projects of your own.