an item in inventory that stores 1 type of entity within it

Hello,

I am trying to make a small mod that tweaks some minor problems within my modpack. I am currently trying to make a procedure for an item that will be in the hotbar, that can hold 1000 of one type of block. I.e, Its basically a /dev/null. I have made a gui, the recipe, the object. I am struggling to make the right click procedure and how to get a player to place any item within the item and its store it and picks it up when its on the ground. The player then should be able to see the number count and be able to take it out of that inventory too. 

I would really appreciate the help, if any coders know how to implement this. This mod procedure is for 1.16.5. 

Kind Regards,
Kaito8464