How to make second item shipping cheaper in Woocommerce?

Hi there! If some can help me, it would be very appreciated!
I have 2 shipping classes (light and heavy, let’s say). The option i need to setup is when people buying not one, but few items, i’d like to do shipping price get cheaper if people buying more the one item. Not bulk, but could be different items.
Let’s say, per item shipping cost is 5 euro. When people buy few items, i want to make shipping cost of every item a bit lower, like 3 euro, for example. Easy. But seems to be impossible on Woo, no?
This option is very common for other e-stores (have current store built on BigCartel), which is pretty logical. But i have no idea how to set it up on Woocommerce.
If anyone could help?
Thanks!