I placed an object in my rented skybox and it disappeared and can't be found

[Nooseslt Helgerud]

I even had the sim owner join me in looking for it.  We also went into view and activated beacons, to no avail.  What options do I have for getting it back?  It was a fairly expensive item of furniture

[Rolig Loon]

I hate it when that happens.  There aren't very many places for the stuff to go, though. 

One place is right back in your inventory.  If you were near the prim limit for your parcel, the servers should have refused to rez anything that would have put you over the limit.  Usually they do, but sometimes they will rez an item, realize the mistake, and throw it back to you.  If that happens, it should be in your Lost & Found folder.

If you rez an item that is physical and phantom, it can drop right through the floor of your skybox.  If it does that, it should end up on the ground immediately beneath it.  You should have been able to locate it by using beacons or top scripts (if it was scripted).  If it's not, then beacons won't help.  A friend with Firestorm or Phoenix will, though.  Just ask them to use Area Search and look for it by name or by your name, as owner.

Objects will sometimes end up in the sim's garbage collection area, for reasons that seem more like magic than anything.  It's the default spot at <0.0,0.0,0.0> (the sim's SW corner) where the servers tend to park anything that they don't find a place for.  I check my sim's garbage area periodically and always find something there.

The other possibility -- wierd, but I have done it -- is that you didn't rez the item at all but accidentally dropped it into the contents of some other object.  That can happen if you hold down the CTRL key when you drag/drop something from inventory.  That particular combination is a quick way to deposit the object in whatever you dragged it to.  We do it deliberately all the time with drop boxes.  So, check the floor prim (or the root prim) of your skybox.  Select it with your Build/Edit tool and open the Contents tab.