This is an interesting idea and one that I would support. The only problem, I suspect, is that this will make products appear more expensive since you will now fit (and charge for) more content in the “same” space as before. From a marketing perspective, it would be better to have less product occupying a larger space.

In order for this concept to work you will have to prove that the value in packaging stuff more densely outweighs the risk of appearing less valuable to the customer. Maybe a well-designed advertising campaign will do the trick? Of course, if you have stumbled on some huge efficiency and you can afford to sell the larger square containers at the same price as the round ones, then you should succeed without any problems.

The aseptic packaging of milk is getting close to a square shape. Orange juice and the like are also rectangular.

I don't think I would choose a retangular can over a cylindrical one, I like the feel of a cylindrical can in my hand, it fits nicely and I can spin it around. Also, cans roll out of the vending machines nicely. Corners dent easily too.

I believe that metal cans are cylindrical to conserve metal(less surface area per volume). However, the cost of the metal now is probably cheaper than it was when cans were first invented(tin then versus aluminum now.)

Just a note of information. I believe the beverage that uses the largest number of cylindrical containers is soda. The cost of a soda can to produce is significanlty higher that the cost of the soda inside the can. The weight of the metal used in the can must be optimized to keep the cost of a can of soda low. Hence the cylinidrical shape. Unless you are willing to pay 50% more for a can of soda...

There is another problem, re soda cans. Soda is under pressure. For any non-circular cross section, the pressure tries to force the cross section into a circle, to maximize the volume to surface area ratio. With cylindrical cans, the cross section is already optimal, so there is no bulging (except at the top and bottom, which designers can easily avoid by making these parts stronger). For a square cross section, you would have to make the material much stronger, to prevent bulging. And that would make the cans heavier and more expensive. This in addition to the greater surface area to volume ratio, that a previous reply mentioned. Food cans aren't under pressure after they leave the factory, but food is cooked in the can at the factory to sanitize it and the contents are under pressure during cooking, so the same issue re preventing bulging applies. Too bad, square cans would save a lot of space everywhere: In transit, on store shelves, and at home.

The reason that the shape of the can is cylindrical lies in a mathematical function. The producers use less materials in the can (namely aluminum when talking about soda cans) a cylindrical can than a rectangular can, thus decreasing their costs. Yes, there is a waste of space factor to be added in, however, in the long run, cylindrical cans save the companies more money.

How do you use a can opener?

I think that you would have to put twelve welds on a cube or rectangular shaped metal can which would make it much more expensive to produce.

What welds? The base of the can is one-piece, shaped with dies. The cans are completely seamless from top piece down. The only real disadvantage to the square can idea is the lack of sidewall strength, which may possibly be remedied by ribs in the side. I don't see why the square cans could be used for orange juice, lemonade, grape juice, and other low pressure items.

Let's look over each category:

Efficient Use of Materials: Round cans are more efficient than square, because a circle has greater area for a given circumference.

Storage Density: All-out square wins. No contest. A square with the same side length as the diameter of a given circle has 20% greater area. (hence a can would have 20% greater volume)

Strength: Round cans do not have corners to dent or flat faces. They have curved surfaces, which are more resistant to denting or pressure. Have you ever cut a soda can in half? The actual material is incredibly thin.

Pressure- Round handles it better.

Can Opener: The lid of any can has to have edges rounded enough to use a can opener on. **There is an exception for pull-tabs, but if the can is not rounded then the lid would have sharper corners, which would be even more dangerous than the lid is already. --- As a result of this, square cans lose a large portion of their only advantage over round cans- their greater volume.

My verdict? Round cans all the way.

***** Final Note: Square plastic or cardboard containers are great for dry foods (i.e. cookies, flour, baking soda, crackers, etc.) Dry things are not pressurized and plastic/cardboard do not need a can opener.