Shelf mount for metal plug shelf

This constructions is an easy and cheap way, to extend the storage capacity of your shelf/cupboard.

Why this part? Additional shelves for this open cupboard/shelf (why does english not distinguish between those two parts?) do cost 25 Euro for two pieces, and the whole shelf/cupboard itself was about the same price when i purchased it. I found that quite expensive and so i searched for a cheaper alternative.

I purchased some wooden boards for 4.75 Euro each (luckily already with the correct