TuffBoxx’s mount feet are built into the base of the bin, and are hidden from view. The mount feet are underneath the round swivel covers on top of the base on each of the 4 corners. If possible, it’s easiest to mount the base prior to assembly, but if not, you will need to get inside of the bin to access the covers. Once the covers are swiveled to the side, it is easy to find the mounts. All you will need to do is mark the hole locations for drilling the lag bolts.
You can even drill from the top of the base, but we suggest doing one bolt at a time to ensure that that holes do not drift, and all of the holes will line up with the mount holes. After tightening the bolts, you can slide the access covers back into position.