This my new device Called Smart Item Trade System.
Was inspired on SethBling's Smart Item payment Machine, wich I think it's a really good idea for Adventure maps.
I'm also doing an Adventure map wich will be using this device,can't reveal anymore details.

This device is used to make a shop,wich you can only buy with that certain item required :)

Thank you!

I hope you like,
And if so, comment and give me some ideas about some maps or redstone devices.