This is a tunnel boring machine that you can send out under ground and it will collect all minable materials and bring it back. Once it's back, the resources will be gathered and send to the back of the drill to some TNT duplicators and collected into a chest.

I was looking for a schematic but never found one so this is the one I came up with. It works in vanilla minecraft and on multiplayer servers. It shouldn't be too hard to replicate but if there's a part that is unclear, just drop me a message.

The download is a worledit schematic and the diamond ore block is some teststuff that autorefills once the drill went through.