I can write a lot of code but I am lazy. So what can I do? The answer is Unity assets. There are a lot of ready inventory systems, that just want to be used. I downloaded one of them and then started studying it to fully understand what is it doing. It is necessary to understand, the code written by somebody before to edit it and adapt well. So first of all I had to delete useless for me parts of code add new statements and functions. And now my first prototype of equipment is working (I mean it is doing something). Now it just needs to be developed. My next goal is to add some NPC's because new Sprites arrived from Michał.