1. Usage of the shop system:
Place a chest on the ground.
Place a sign on the top, and edit it as follows:
(If it's a double chest, on both chests!)

1. Line: Minecraft Username
   
2. Line: SHOP
3. Line: Count of costs in diamonds
   
4. Line: Count of items to be given

Done!

2. Safety:
The chest and it's contents as well as the sign on top are protected, external events like TNT and Hoppers are disabled too.

3. Translation:
This Plugin is currently only in german, translation may be added in the future.