So, to start: Gaffa Tape, Super Glues, all weather sealant (Got some down in my allotments shed.)
Various washers and plumbers tape
Extra nails and screws
Spare tape measure and multi head manual screw driver.
Some plastic sheeting/tarps for emergency window repairs
Some Sheets of MDF/chip board/Plywood (Not for the box, but in a corner of the garage!)
Yes I know I could go on forever and make some wonder tool box and supply of materials, but this is basic bits for prepping emergency. I have my forest-school hand tools in a bag in the garage so I am set there for power-down situation tools. I tend to keep "useful bits of wood" in my allotment shed, rather than clutter up hubby's shed where he does his knife making hobby. Might not go down too well if I clutter up his work space