Pics from when I first built mine. I wanted to add a place to put the Viair and Tank. It's bolted through the floor, the fire ext is on one side with a Flashlight mounted on the other.
Plenty of room inside for parts, oil, Straps, tools that don't fit in the small tool box. With the tool box I wanted to be able to pull it out when I needed without lifting the lid.
It's been in for a couple of years now and the MDF is starting to show wear, looking at some of the pics here I may have to rebuild soon.
I also have straps going to the factor cargo mounts that I put on when wheeling, Just not sure how well the latches were going to hold in a roll over.