I built this longer rail because the stock one doesn't support my longer lenses. Its currently 210mm, so it should fit most beds, but if there's interest i could construct a longer one.

I've also constructed a lens support system while keeping the same overall aesthetic. You will need to use the connector on the Outside of your rail extension, connect the vertical side, connect the lens bridge to that, and print two lens rests. All holes are 1/4-20UNC (standard camera screw).

The lens support system is still in progress, as getting a long enough rail while supporting weight has been a challenge. I'm currently in the process of finalizing the next version of this

NOTE:: You will have to disassemble the angle rotating mechanism to replace the arm. To do this, you'll need to:
Remove the three set screws, then the red tightening screw on the other side.
Once removed, you'll need to use a pinpoint tool to turn the nut on the tightening screw side, which is glued into place. (Make sure not to lose the washer! Might also be worth replacing at this point if worn) It's a pretty sturdy piece of metal, so feel free to use a bit of extra violence if it's not giving way.
After the nut is removed, you can unscrew the center bolt (also glued).

There is some form of lube/protective paste (possibly lithium grease?) inside the mechanism, try not to remove any so you don't have to replace it.