On the map Carnivora (Pandora) there is a red chest here:
There are 5 space rocks as you can see:
Or not? Actually there are 7 of them! You can smack any 2 of them to get an extra (or one to get two additional) space rocks.
So to me (with a snowdrift relic with bonus 9% movement speed, and an almost perfect (17%) vagabond shield it is the best eridium farm currently. Teleport to guts of carnivora, exit the map, run to the car station nearby, and go. Before I leave, I travel back to guts of carnivora, because if not, the game will drop me at the start of the map.
(Sorry for the red lines, printscreen and paint hate each other for some unknown reasons)