Simple clamp

You can make a very useful and simple thing for your workshop in just a few minutes - this is a clamp from a piece of profile. It can be used to fix workpieces made of both metal and wood. So if you suddenly need to clamp a workpiece in several places, making several clamps for such work will not be difficult.
There are different profile sizes, you can choose any one to suit your needs.

Will need

A piece of steel U-shaped profile.
Two wide nuts, better homemade if possible.
Long bolt.
A thin, long bolt or piece of steel rod.

Most people have everything in their garages, and if not, it won’t be difficult to buy them at the nearest hardware store.

Making a clamp

It is necessary to cut the required size from a piece of profile; to do this, draw a line along which we will cut.

Cut along the line with a grinder. We grind off the sharp edges.
To make the internal planes of the profile more parallel, we bend the sides with hammer blows.

In one of the sides we drill a through hole with a diameter larger than the thread diameter of the large bolt.

Drilled.

We weld the nut using arc welding on the outside of the profile.

We tighten the bolt to make sure that everything goes smoothly and does not touch.

We weld a thin one on top of the thick bolt.

This will be the handle behind which the clamping mechanism of the clamp will rotate.

To increase the pressure area, weld a nut onto the end of the bolt.

Now the clamp is ready. Let's move on to testing.
I made several pieces at once, it took no more than two dozen minutes. I press the steel plate to the table. Holds up great.

For better performance, a good solution would be to lubricate the threads with graphite or other lubricant.
A significant disadvantage of this design is that when tightened, the pressure sole leaves a mark on the product being fastened, as it rotates along with the bolt. For some types of work this is of course not creative, if you need to avoid this - place a piece of steel under the pressure nut.
All the best!