Custom Multi Select Grid

Good Day,

I’m trying to create a custom post meta box that allows a user to select multiple boxes/cells in a grid view. My idea is similar to creating a multiselect or checkbox group, but I don’t know how to implement all the options.

array(
				"name"			=> "grid_options",
				"title"			=> "Test Grid",
				"description"	=> 'Select the options from this grid',
				"type"			=> "grid",
				"scope"			=>	 array( "post" ),
				"capability"	=> "edit_post"

			),

…customFields function case:

https://pastebin.com/QRHXrCs5

This only displays the table as I need it, the <input> code is where I’m having an issue. I can use jQuery to manipulate the value of the input when a user clicks on a table cell and it posts the array, but I don’t know how to store that array of selections into the post meta when the post is saved/updated.

I’ve thought of using a “checkbox group” but from my understanding, then I have to specify all 1152 options before-hand in the meta-box array, which is definitely not ideal.

Any idea’s on how to accomplish this would be greatly appreciated.