Configurable product based on A LOT of attributes? Am I doing this right?

I have a customer who wants to use products in the same way configurable products works, pretty much.

The problem is that the customer would have to use a lot of different attributes. Let's say he's selling custom sized papers (for some reason haha), these comes then in... let's say maybe 30 different combonations of X x Y mm (10x20mm for example).

Then another product would also use mm, but no the same. Let's say he is also selling envelope in customer sizes, these does not match the sizes of the papers so I need another 50 combinations of sizes for this product.

Is this how it usually works? Or am I using wrong product type / wrong way of doing this?

Do Admin configuration for simple product as per below screenshot

customer will see