I copied the design for this record changer work stand from someone on the internet. I think it was Bill Turner, but his web-site is gone so I can't check.
The supports just slide together, so it is easily adjustable.
It gives plenty of room to examine the mechanism from below.
I made it from 1 x 2 and 1 x 4 maple boards from a local big-box hardware store. If I had it to do over again, I'd use 1 x 6 for the center piece to make the stand a little more stable.
I glued and screwed it together, careful to keep everything square.
I mortised the ends using a tenoning jig on my table saw, but some careful work with a back saw would do the same.
The edge of the changer base fits into the mortise. It's surprisingly stable, but as I mentioned before, I'd space the two supports a bit wider if I were to make another.