How to add multiple images to a custom post type single post?

I have created a custom post type and I need to add multiple images to every single post, so I can create a loop and use them in a slider. So far my search on Google etc. has turned up nothing.

What’s the cleanest way to add a metabox to the custom post type, so I can add images to the post and create a loop to display them in a slider/gallery?

Thanks for the suggestions, guys. I did some more research, and found this – https://wordpress.org/plugins/attachments/

It’s a great plugin that lets you attach images to the post without inserting them in the post and the images can be easily sorted with ajax, it’s also quite modifiable and just what I needed, and works on custom post types. You just create a loop and you can use the images in any slider.