A convenient way to set up and display related products for specific products

Hi there,

I've done a fair bit of searching around the forums and havent found anything yet, the closest I have come is this:

https://premium.wpmudev.org/forums/topic/related-featured-products

However the solutions mainly deal with featured and 'best-selling' products.

Is there a fairly straightforward way of setting up the logic for related products? I was thinking of using tags, but thought that this system might get confusing as time goes on. I feel like the sam e might go for categories too - Ideally when uploading products the user will be able to select related products from a list.

Thanks in advance,

-Matt