The last low aluminum tile was in the water patch to the right of PBHead's base, about 7 or 8 tiles away. It was a low alu/low water tile. I did not take note of how many iron tiles were nearby. I think it was two separated high tiles.
Being entirely retrospective about prepared founds:
Expansive, squashing most of the aluminum patch, is a good pre-found. I tried figuring out whether a robotic found would work there as well, but the best found I can see leaves four aluminum tiles open.
If the opponent goes scavenger (in this case PB) on the carbon, you can insta-gank.
If the opponent goes expansive on the aluminum before you, you can found robotic and attempt to steal iron (trouble!) or go robotic.
If the opponent goes scavenger on the aluminum before you, you can attempt to found on the carbon or go robotic.
The other prepared found would be scavenger on the carbon, so that:
If the opponent goes scavenger on the carbon before you, you can attempt to gank (in this case DeathTacticus) or go expansive/robotic.
If the opponent goes scavenger on the aluminum, you can insta-gank.
If the opponent goes expansive on the aluminum... you're in trouble. You can swap to robotic and attempt to steal the iron (risky!), or stick with scavenger. If you do go scavenger, one (silly) option is to found on one of the iron spots.
Assuming you prepared scavenger on the aluminum:
If your opponent goes expansive on the aluminum before you, you're in trouble again. You can found robotic and attempt to gank, or go with scavenger and attempt to grab some a low tile and get by.
If your opponent goes scavenger on the aluminum before you, you can try to gank the carbon tiles or found expansive/robotic.
If your opponent goes scavenger on the carbon before you, you can try to swap quickly to expansive and found on the aluminum, or otherwise go expansive/robotic somewhere else.
TL;DR/Summary
The constant seems to be that founding expansive on the aluminum and taking the two high tiles immediately is a dominant position to be in. Another weird thing you could do is try to found expansive on the carbon, grab the iron tiles before your opponent founds, and let them have the aluminum. What are they going to do with it without access to iron or carbon, anyways?
edit: This is only if you plan to ignore all other found spots on the map.