At the Brigade Quartermaster web site under Boxes, Containers, they list a Can Keeper for about $5.00.
Seems that it caters to anyone who likes to chew tobacco, but it is much more versitle than that.
Waterproof, carried on the belt, made of OD plastic, it could be an alternative to an Altoids tin. Noticeable, but perhaps more comfortable than carry a tin in a pocket.
According to write up, it can carry a 35mm film cannister, so it does have some depth to it. Also seems to have a piece of metal embedded in it for opening chew. Could be used for other jobs I imagine.
Almost looks like a handcuff case.

FWIW

If you are considering "belt-ware" in that size range I would think that the surplus jungle FAK pouch(no dimensions listed but I think it is 3"X5"X2") would be better. If you wanted it waterproof you could line it with a ziplock. The soft-side nature allows for a much greater flexibility when packing it. I imagine that the paint could be coerced off the outside or you could find one without the paint at your local surplus dealer. For something slightly larger you could look at this surplus bag 6"X4"11" with tunnel loop at the back for belt wear. Both of these are to be found for under $5 at majorsurplusandsurvival.com. With a very little sewing the larger one could be turned into 6"X4"X6" for smaller, more discreet, carry.

Also comes in black. Looks like it would slip on and off a belt without having to remove the belt.
Not sure how it would fair in cold weather. Also think the plastic closing device would wear thin after a while.

removing from belt easily is where Alice clips come in!

What about a fanny pack? Also, most of these PSK's seem to be geared toward 'personal' survival but I bet we will end up using our tools and skills to help others (family and friends) more than ourselves. For this reason I always have a keychain size CPR mask and keep my CPR cert up-to-date. You can get these from your local redcross for cheap.

look here for a picture

I like the altoid box a lot though. I have a heart shaped one but it's still full of mints.

For everyday carry, I think Alice clips might be a bit rough on a decent belt. I would tend to avoid them.
But, it depends on how one dresses for work I guess.

I guess it depends on how much you want to carry and how you want to carry it.
There are a number of generic digital camera cases that would do the job and in being used, would look just like a camera on your belt, nothing else.
Of course, if someone ripped you off for your camera (sorry, I live in L.A.) they would be surprised as to what they got.

One of the pluses about some of these cases is that they have a snapp loop that allows them to be put on a belt without having to undo the belt to put them on.

FWIW