To make a round (or cylindrical) cardboard box with your own hands, you need to know not only the basic principles, but also a couple of simple tips, which I will now tell (video attached).

So!

First, I clean the cardboard from tape and other labels. And, what is very important, I choose the most flat surface without bends, they can be cut.

Multilayer cardboard is put aside, it does not fit me.

I will use a classic, single-layered one, but durable.

For quick work, I use a ruler on which I mark the radius of the product with a compass, given that its diameter will be twice as large.

And now a minute of interactivity: write in the comments who works with a stationery knife.

Personally, I do not use it, because the width of its blade is too clumsy (wide) to cut a circle. But even if
adapted, the result is not always happy. It might not be that visible on a large circle, but in my case it won't work.

Tip: use a scalpel.

The blade of this hard worker is much thinner than a knife, so the work goes faster.

What is most valuable, it is metal, so it will last a long time. With a good tool the work is a pleasure.

So, I cut out a perfect circle in 2 copies. This will be the bottom and lid of our future product. Carefully determine the height for the entire product and then the question arises: how to determine the length of the cardboard piece, so that he rounded our circle?

Correctly. Multiply the diameter of the circle by 3.14. So I got the necessary length, which I divide into two parts: the top and bottom. And with one, and with the other part of d work separately.

It's time for secrets: to make a cardboard sheet bendable, I make an incision between each wave of corrugation of the upper paper layer.

Gently, slowly, with the tip of a knife. Due to the fact that the lower paper layer remains intact, the design does not
disintegrates.

By making incisions along the entire part, I obtained a bending line or "caterpillar one-sided", which, if necessary, can be rolled into a spiral or ring.

I almost forgot, the lower part we also turn into a caterpillar and, it would seem, everything is clear, but there is another secret that will help hide the cuts on the cardboard, which are visible when bending the line.

Remember how the scales of a fish are arranged, how one overlaps the other. If we achieve this effect on our cardboard line, then it will turn out to bend it in the opposite direction, the smooth side outwards.

Now, with the help of hot glue, fasten our "caterpillar" to the cut circles. In such places I often use hot glue, as it catches quickly.

I would recommend working on a special surface or on the one which is not a pity to stain, because the glue leaves traces. Excess cardboard cut off with a knife.

To "roof" boxes are not blown away by the wind, I take a piece of cardboard, in my case, a single layer, but with waves of smaller caliber, cut the "caterpillar" and paste inside the bottom of the product.

So it turned out a full-fledged cardboard box with their own hands, however, without appearance. Write in the comments if you like this format.

See you soon!