I went to mount a keyboard tray underneath my desk, and discovered that the desktop was hollow (despite what the sales guy said... Guess I should have trusted my instincts).
The desktop piece is a hair over 3/4" thick.
The tray is intended to mount with 3/4" long screws (these don't quite break the surface when the mounting bracket is factored in), but there isn't enough material inside the shell of the desk for the screws to grip on to.
Looking online, the best I could find was someone with a different type of desk finding some studs inside the desktop. I'm in the process of getting my hands on a stud finder to check on this, but for now I'm assuming it won't be an option.
A friend suggested pushing a bolt down from the top of the desk, with a washer above the desk to help distribute the weight. I'm okay with the bolts disturbing the surface of the desktop (it'd be outside my work area), but I'm not sure of the aesthetics. I'd also like some idea of how well this would work before drilling more holes in the desk.
An ideal solution would be something that I could insert into the interior space of the desk for the original mounting screws to attach to. But I'm not sure that such a thing exists, or that it would work in this case.
I'm also open to other suggestions.
Note: Apologies for not including a photo. I just wasn't sure what to take a photo of. If there's anything that needs clarification in the above, please let me know.