Easy elbow joint?

Hi, I'm making an indoor trellis that's changeable- repositionable. So it involves an elbow joint between two 1" by 2" by 4' boards of wood. I'm a total beginner and don't know what I'm doing.
So, I want the two boards of wood to be connected but able to rotate, the way your forearm rotates around your upper arm. I also want to be able to "fix" the joint in place, so that it's immovable, but then easily loosen (unfix) it to rotate it into a new position. Am I explaining this terribly?
Maybe this will help- My original plan was going to be this- Where the two boards of wood meet, I was going to just put one nail to connect them. That way, I could rotate the "forearm" of the elbow around. Hence, an elbow joint.
And then I thought that would be too loose, so I though I'd put two nails in, and when I wanted to reposition the forearm, I would take one nail out, and then move it into a new pose, and then put the nail back in.
But then I thought this is probably a common problem and there's something I can buy at home depot that does this? An elbow joint that can be "locked" and "unlocked"?
thanks.
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Flexor wrote:

A bolt with a thumbscrew or wing nut.
--

dadiOH
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