Heavy duty boxes for cakes

This is the place to get boxes that are heavy duty and come in all kinds of sizes.

http://www.tharco.com/index.shtml

You can also find these exact boxes at packaging and shipping stores, like the UPS Store, or even the post office.

If you look at the Tharco site, they make custom boxes too, even with a logo if you want. 

The amount of time the cake is going to spend in the box mostly will be while it's in transit and storage. The basic function of the box is to protect the cake and transport it. Your "presentation" is a beautifully decorated cake that will be viewed outside the box. So why spend extra money on packaging if you don't have to and if it's not needed? Granted, cakes that are on display in grocery stores need pretty window boxes, but that's to increase saleability. If you notice, a lot of stores are going with clear plastic packaging to showcase the whole cake rather than cardboard window boxes. 

But I'm assuming you're a custom cake decorator and do cakes by order only. That is what I've done in the past, and as a decorator, I'm more concerned with a cake that arrives at it's destination the way I decorated it, not with gouges and smashed parts. If the client ordered the cake from you I'm sure they're more concerned with a pretty cake, not a pretty box. Just my humble opinion (based on experience).

I agree that it's not that important how you get the cake to its destination as long as it's intact. Frankly, the client doesn't care about how it arrives as much as how it looks when it's delivered. I took a decorating class taught by a well-known pastry chef in the Bay area who delivered her cakes in large cardboard boxes lined with styrofoam (sp?) to keep them chilled until they were assembled (some of them had to travel over an hour). Not pretty, but it got the job done. And we all know chilled cakes deliver and assemble better.

I have never had a problem getting heavy duty cake boxes.

There is colored double wall.

Odd shape gable boxes.

Would never deliver uncovered.

I don't really know what cement board is but sounds like chemicals.

pan

I was in need of a larger box recently and the kind they use for record storage (Staples) was great!  A similar one is available through Tharco:

RF5  24-1/2 x 15-1/4 x 10 with Lid attached 
      (Double Bottom and Triple Ends)

But Staples has them, too.  http://www.staples.com/Bankers-Box-Presto-Storage-Boxes-Legal-Size-4-Pack/product_736545

You can put the cake in the lid, and put the box on top of it, fitting just down inside the lid--plenty of space above the cake for decorations--it's 10" deep.