Next gather the items that you want to include in your can. You may want to place your larger items up next to the can to make sure they will fit and that the can will close securely. I will be using mine along with my LBE ( load bearing equipment) and my condor urban go bag ( highly recommended bag, cheaperthandirt.com). Since I have an AK 47 (wasr 10 63) I will of course include my AK buttstock cleaning kit. I'm also packing extra batteries and spare parts including a firing pin.
You can make a different kits to fit your camping or tactical needs-
first aid items other tactical items camping kit sewing kit fire starting kit
Other things that you may want to include to fit your needs.
Rem wipes ( I will probably add these to mine) sewing needles small spools of thread tender lighter matches bandages (why would you put these in a band aid can right?) gauze toothpaste alcohol swabs tweezers fingernail clippers whistle signal mirror etc.
You may want to stuff some lint or a piece of fabric to keep small metal parts from clanging together if noise is a factor.