Collision problems

Hey guys! 

Im pretty new to Gh but managed to program my first piece of furniture.

It`s something made out of metal wires and Boxes, the main problem is that i can't control the collision in between the boxes wich i populated on the surface. I'm browsing for days now to find a solution but i could'nt find anything [suitable to my skills :D]

maybe one of you yould help me to find the solution? I'll attach the file 

cheers!