How to create my own shit coin?

seriously!

I know there is not point in making shit coins I just want to do it for learning purposes and to use it as "points" in a CTF challenge I am hosting.

I found some videos online but those are using an existing blockchain, is there a way to do it all locally I mean by selfhosting or something? as you can see I have very rough idea about shit coins. so yeah!

feel free to share your shit coins too!