I designed this shelf considering that all the tv's are not the same, so made the arms adjustable.

You need to print the arm, extender, and extender cap twice and the knobs 6 times. (if you want to use knobs, because you can use only bolts and nuts).

I used M5X10mm bolt and threaded inserts.

2 threaded inserts for the shelf

2 threaded inserts for each slider (call it slider, idk the name for it loll)

The M5 bolts, i press fit them into the knobs by heating them with the soldering iron, same as the threaded inserts.

I'm still testing the shelf, it holds my T-rex easily, put stuff on the shelf at your own risk, as i don't know the maximum weight that the shelf can hold.