Kai Zen or continuous improvement applies here too.   Start with an
empty box.  As you remember what you've done already and if you can
remember what hand tools it took, put those in the box.  This is an
ongoing project.  The 512 piece master mechanics set from Poonyang is
not what you want.  One of the most important pieces is an annotated
Bently manual.  The annotations are the changes you've made over the
years of your passionate realtionship with your road diva.  Especially
added electrical bits.  A perusal of Zen and the Art of Motorcycle
Maintenance has some good ideas too.  Add to the trove as you imagine
future adventures.  Learn to use the tools in some reasonable manner.
Make a list of the tools an keep it in the box with a copy in the
Bently.

The basic wire, cutters, snipenosed pliers, goose tape, adhesives and
some genuine cloth electricians tape will get you a long way.  Hose
clamps and dont forget that golf tee.

A very good led headlamp and an extendable inspection mirror are
almost essential for those murphy driven repairs that must be done in
a mirror, at night, underneath in the rain.

I use a slider board made of that odd material that some signs are
made of.  Looks like plastic cardboard.  Slippery, hides under the
rear cushion always at the ready.

More of course but the Bently will help even a modest mechanic
understand your Vanagon, after all he is a mechanic and that applies
across the board, with the details he can probably do whatever is
necessary.

Pensioner.