I've got one similar only it's a "go box".  Just a tackle box with all the assorted items.
 
However, I also make a habit of asking myself a few questions before backing out of the driveway.
 
Did I pack:
Gun?
Powder?
Patches?
Balls?
Flints/caps?
 
It's a great habit because I do it before heading out for the day's hunt - whenever I take my muzzle loader whether it's to the range or woods.  While I'm asking myself these questions I envision whether I checked the status of the powder horn before loading it, whether I checked the ball-bag, patch material, and cap tin.
 
Gun, powder, patch, ball, caps/flints - the rest is just fo-faraw.