Fastest Method of Digging at Low Levels?

[Zetapup]

What it says on the tin. For a future campaign, I plan on having a horde of constructs digging/mining and using whatever useful materials they collect (iron, adamantine, mithral, etc) to make more constructs and begin an exponentially increasing cycle. However, I'm not sure what the quickest method of mining would be. My first idea was warlocks with baleful utterance, but that's basically shatter and shatter only targets a single object up to 10 lbs per caster level (the 5 ft radius only works against more brittle objects), so I'm not sure if that would even work for digging. My second thought was to use Mountain Hammer, from ToB, but that requires them to be at least 3rd level and would only be useful once every 5 minutes unless you count mining as an encounter.

So, any advice for what a bunch of 1st level constructs should be in order to maximize digging efficiency?

Edit: The constructs are going to be a homebrewed race similar to warforged, so they're intelligent/can gain levels/etc.

[Gavinfoxx]

They shouldn't be constructs at all.

They should be Unseen Crafters and Unseen Laborers from a custom-researched Laborer version of the spell, created from a repeating magic trap, with someone who is the best miner / laborer / digger you can find triggering the trap.

Also, for exponential, you wanna read this:

https://docs.google.com/document/d/1aG4P3dU6WP3pq8mW9l1qztFeNfqQHyI22oJe09i8KWw/edit

And what do you mean by 'first level constructs'?

If you want to know what constructs you can ACTUALLY MAKE, read this:

http://brilliantgameologists.com/boards/index.php?topic=177

[Zetapup]

And what do you mean by 'first level constructs'?

If you want to know what constructs you can ACTUALLY MAKE, read this:

http://brilliantgameologists.com/boards/index.php?topic=177

Ah, my bad, they're essentially warforged, so living constructs. I should have mentioned that they're going to be a homebrewed race in the op.

Thanks for the other stuff! I'll give it a read and see what fits.