Ammo boxes are readily available on the civilian market. You can buy them anywhere. Any military surplus store sells them. You can buy them on the internet. They cost around $10.00 apiece for the .50 cal. size.
You can usually put two 35mm sized cameras in one box or one camera plus a few lenses. Two Rolleiflex sized cameras will fit comfortably in one box with room for a few accessories or rolls of film.
When I inherited my camera collection everything was in ammo boxes. There are a little over 100 cameras from Baby Brownies all the way up to a Graflex. The Graflex came in its own wooden box but 90% of all the other stuff fits in ammo boxes.
But for the few things that don't fit in ammo boxes, everything fits inside 40 ammo cans, .50 cal. size.