This is more of a "complete remodel inspired by" rather than a remake of Cregory83's and iplo's Ryobi battery holders.
I designed it in OnShape and you're free to take and extend that model to you heart's content.
The mount holes are intended to align with various types of “square” (not “diamond”) pegboard using both a one inch and 12mm grid to align the mount holes. NOTE: I don't have any pegboard to test against, so this is largely guesswork. I expect the most likely problem might be the screw hole diameter.
I mounted my two using a single 8G screw each into a plywood panel (because I only had 2 8G screws to hand). This is nevertheless plenty of attachment for a 5Ah battery.
Also posted to Thingiverse.
The author remixed this model.