Playa Vault

[robotland]

The best place to keep valuables is ON YOU or IN YOUR CAR....But if you desire a convenient and somewhat secure in-camp stash for your goodies, score an old ammo box. Still portable to the sticky-fingered, you deportablize said box (bigger is better, or at least easier to deal with) by first drilling a hole in the bottom and then pounding a piece of rebar through the hole and into the playa. The other end HAS TO BE CANDYCANED for this to work. A stake with a capped end will work too.
Another technique involves the use of two of those screw-into-the -ground anchors and two hasps installed on the sides of your lockbox- Screw the anchors into the ground so the exposed loops are apart by the width of your box. Then set the box in between, and snap a padlock around each loop AND hasp. Since there are two, and they're locked down, they can't easily be unscrewed. in fact, it's hard as hell!
Don't forget that for either of these to work, you'll have to be able to LOCK the box....most ammo boxes don't come with lock hasps, but they can be installed in about ten minutes. I like using stainless steel rivets and washers for this, but plain bolts will work fine.
Now that you've got a highly secure goody box, make sure that you know where the keys are.
ONE MORE CRUCIAL STEP:
In fact, if you don't worry that much about theft, just DO THIS STEP....Disguise your stuff to look like less-valuable stuff. Don't hide your goodies in a beer crate, since beer goes missing with high frequency in BRC. Hide it in a highway cone. Or in a plastic bag inside your kitchen-trash-being-dried hanging mesh bag. Be creative. Don't be so creative that you forget, and toss out good stuff. (Something the wife was concealing almost got "cleaned" when I threw out the old dip container it was in. Had to crawl in the 'curby on that one!)

[Martiansky]

Sounds like geo-caching to me!

[AntiM]

We keep a small "dry" cooler in the jeep for stuff that needs to be cool, less dusty and not wet. Film, batteries, medicines mostly.

[unjonharley]

To feel real safe, Drill a hole in the bottom of a metal box and on through the floor board of the car. Run a carrage bolt up through and nut on the inside. Lock the box. Or the other rule of thumb: If you can't afford to lose it. Don't bring it..