I assume there's some kind of magical knack to getting holes in the right place when drilling metal...

If you're making lots of piece of identical ally bar, is it worth making yourself a little jig? A scrap piece of metal (or even plastic/wood) with some 2mm through holes drilled in the exact right places. Clamp it to the piece you're working on, then use the pre-existing holes to line up a 2mm drill bit. You'd only need to go in a couple of mm on each hole with the jig in place.

Might be a bit of a faff to make but that way you only have to be accurate once.

Oh, and the robot looks awesome!