Just google 'rolling tray' like I did. Looks like they are being sold everywhere so I'd do a price comparison first. Also, in the future if you see something posted you want to investigate you can drag and drop an image into Google Images now, to match it to content elsewhere.
http://www.wolfproductions.net/
Wolf Productions (YAY!) seem to have made theirs the most standardized, iconic sort of design. Many more seem to have imitated it. I'm sure there's a bunch of different sizes and configurations. From the picture it looks like you can slot things in a nd out at your leisure, too.
If I buy myself one, I'm going to get my woodburner and put some patterns in it, maybe a big wolf like my avatar. I could burn/engrave some for you guys too maybe.. They only offer logo printing with an minimum order for promotional purposes.
Oh, and many of you have the necessary skills to make one, I'm sure. I did good in wood shop but I don't have the tools. Maybe we should have a rolling tray making contest/ultimate stash box making contest.
Oh god, it comes in pink.. WANT! And just a little box with a kief tray for at home. I realize how much kief gets wasted in my canisters.
http://www.wolfproductions.net/s3hemp.html#
And Mike and Naomi you might have to just make something or stick a tray under a silk screen (used for t shirt printing) if you want large surface area. It makes sense if you're handling alot of buds and the kief is just going all over your carpet, wasted