So what you first need to do is dig one block down put a rail in that hole. After that you take a chest in a mine cart this can also be hopper, TNT, and more depending on the design you want it to be. Next you place the mine cart with a chest on the rail and put a carpet over it the mine cart would make the item stick out onto the carpet making a chest carpet same would happen with a TNT mine cart and other one's. They also make good decoration for a server or map.


Note: This does not work with regular minecarts