Hi Racta, welcome to Polycount :) Do you mean what is required to make a 3D model, or how you can convert a 2D image to 3D? If you give us an example it would be a lot easier to answer.
Good idea! Here is mine. It's similar to my Polycount sketchbook with 2D + 3D but all the finished stuff as well: https://www.instagram.com/derrazputin/