My wife made me a bag a few years ago
It is a long rectangle of heavy cloth about 1.75 - 2 meters by 0.75 meters (you are in Canada, right?).
On the anterior side, she sewed on a second piece of cloth 1.25 m by 0.75 meters. So now you have a bag 1.25 by 0.75, with a 'hood'. She then divided the bag into three compartments lenthwise. Each compartment can hold a couple of weapons.
She also sewed on a small pocket on the anterior portion of the bag that is big enough to hold a tanto. This little pocket has a velcro clousure.
To fold the thing up, you fold the hood over the anterior of the bag so the weapons don't slide out of their pockets, and then roll the thing up. On the back side of the bag there is a long shoulder strap. There are also two straps with velcro that wrap around the bag perpidincular to the length to keep it from rolling open.
It works pretty well.