DEWALT 20v Battery Pack Holder - Horizontal
Adapted from George-Corrigan's excellent design. Print vertically as shown then rotate to the horizontal. The face touching the bed-plate has two holes for screws into the wall. It can be mounted with the battery facing up or down. As there is a chance that a horizontal orientation may permit the battery to be shaken out, there is a groove to engage with the battery lock to secure it.