How do I connect profile pipes without welding and bolts (2 ways for 5 minutes)

Two years ago I created this channel to share construction and repair life hacks, and only today I remembered that already I have long wanted to talk about two ways to connect shaped pipes without a welding machine and furniture bolts: the first one is simpler. The second is more difficult.

I'll make a reservation right away that if you didn't hold anything heavier than a computer mouse in your hands, it will be difficult to make such connections. But you can.

Method one.

You can use a variety of fasteners "crab". It is called so because it has several (at least three) branches. The whole range of such fasteners is in the photo above (photographed at the Togliatti technical school).

Of course, the method is the easiest of all in my collection.

The second method is more complicated.

Step one - cut out a square hole in the first profile pipe, which exactly matches the dimensions of the second pipe:

Step two - turn the pipe over and make two parallel cuts along its edges.

Step three - we take the second pipe (which has not yet been cut), and from its edge we cut off two opposite ends.

We insert the second pipe into the square hole of the first one:

Step four - on the reverse side of the structure with a hammer, bend the "antennae" we cut out in the second step:

It turned out to be a pretty reliable connection. Of course, there is some backlash, but in some designs it does not matter, because we connected the pipes without welding and bolts!

Your opinion?

I would be glad to receive your comments.