How to pack an arduino project in a box

I've seen Pelican cases being popular for this kind of thing. There are some videos of people using them: http://www.youtube.com/watch?v=9f8nwwCbfRA and http://www.youtube.com/watch?v=3MGRx9KDDg0

Otherwise, to make a sturdy Arduino circuit without a breadboard, I'd suggest using Perfboard to solder the components in. Check out http://www.instructables.com/id/Perfboard-Hackduino-Arduino-compatible-circuit/?ALLSTEPS for a great tutorial on doing this. It is more work than a breadboard, but not too much and worth it for a very solid Arduino device.

I know this is an older question, but I thought I'd throw my 2 cents in anyway.

I, personally, wanted a nice enclosure for my Arduino based project, so I gutted an old cable modem I had laying around, mounted some standoffs with gobs of epoxy, and it has turned out great so far.

You could find a project enclosure at a local hobby shop, or gut some old electronic gadget you have laying around similar to the way I did. You could always surround any opening(s) with a bead of RTV silicone; this should make it fairly water/weatherproof, and if you need to change the circuit, you could just scrape the RTV off and start again.

When I've wanted to use a patch board for a demonstration unit that I use elsewhere than just on a test bench and I want it to be "modestly robust", even though the wires are plugged in and not soldered, I have on occasion added a sheet of foam on top of the wiring and components and then sandwiched the whole assembly between two thin sheets of wood or plastic, with long screws pulling the sheets together and compressing the foam enough to hold the wiring and components in place. This is very "unprofessional" but surprisingly effective. Remember to account for lack of cooling due to foam "insulation".

Obviously this does not confer "waterproofness" (not much anyway :-) ) - you still need to mount the "unit" in a suitable enclosure.

Even when a proototype HAS been soldered I have used a simila system to reduce the effects of people playing with the circuitry during testing. To soldered board add a sheet pf suitable plastic and retain with screws at each corner and maybe through several centre points if large. Works wonders.