On that line, I would like a two or three level socket rail that pivots like a drill index for long bit sockets. They lay flat when pivoted down to fit in the drawer, but can be turned upward when the drawer is open. You could get 2-3 layers that way
Per part 43 app A, painting is considered preventive maintenance, which should allow you, the aircraft owner/pilot, to sign off. Weight and balance/flight controls will be through your AMT friend.
Where are you located?
I've been in aircraft paint (commercial and military) for a couple...
Mine (from the Navy) isn't steel. When I was in, they were used for different tool box "kits" (flightline hand tools, hydraulic adapters, etc), and had inserts in them. You would check out the whole box for the job. Very heavy duty, though.