Any tutorials around this kind of plugin?

Basically I am trying to build with the code structure of this:
https://www.ads-software.com/plugins/ultimate-responsive-image-slider/

But not with the layout, I am using something completely different from what the plugin offers. What I am trying to get down is the custom post type it uses. The drag-n-drop images and the custom meta-boxes. This is surprising more difficult that I expected it to be.

I thought I had a tougher time building the JavaScript library but that was nothing compared to this.

No scripts please. I am building from SCRATCH.