There are quite a lot out there actually, but not many of them are free, so you may want to ask Shawn about his.
Jeff at DragonForge used to do them but I think he's doing resin only. Some of the larger scale mini companies like Andrea make them, but they may be too big for you.
I do them as well, as a hobby thing, but I think the quality is pretty good. Here is a link to the page about my transport box, there are pics on there of some of the bases I've done.
http://www.crookedeye.net/forsale/box/box.html
If you are near any military and historical miniature type shows, they usually have a couple of vendors there selling them too.
Zach
www.crookedeye.net