REQUEST: Storage Inventory Filter

I’m looking for a specific functionality (if it already exists, please advise):

My aim is to have a storage container that will contain one of each item that will refill if I remove said item from the container. To do this, I would need to specify a filter for an inventory slot of the container as well as a switch that tells the container to output any input it cannot fit inside. I don’t want an infinite storage, just the option to set what goes where and to scrap the excess after it has been processed.

Does this exist? Is it hard to do?

Thanks!

Put a smart splitter (or programmable splitter) on your input and connect it to three conveyer Belts.
set the exit going to the conveyer going to the container to be the item you want e.g. Iron Plates
set another exit to be “Any Undefined” - in case you get Iron Rods for example and
set the last splitter to be “Overflow” where it will send stuff if the exit it would have gone down is full

Repeat this set up for each container

This functionality is in the base game.

This will have one container per item, which isn’t exactly what I’m looking for.

I would like a single container with one of each inside it.

So, you want to have a single container containing up to four different resources which will feed a mixed belt into a single machine (ignoring the other ports on the machine). This container will be fed by a mixed belt or (up to) four single belts from where the resource(s) is/are made/mined.

Correct?