My first traveldor was a tupperdor. A long (9") container about 6" wide and about 2-3" deep. Kept cigars in an empty cigar box (could actually squeeze three smaller boxes in the tupperdor) and kept the humidity element on the side inside but out of contact with the cigars. Had to watch out for conditions getting too hot in the ambient temperature because then the tupperdor would get just as warm. Overall, it required a little vigilence but it worked well.
Nowadays, we have better humidifier elements (such as the Paradigm, etc...) and better digital hygrometers (Little Havana) that can keep track of highs/lows.
The idea behind a good humidor is that it should allow miniscule amounts of moisture to escape, thus setting up a small degree of circulation. A tupperdor can't do that, so the occassional cracking the lid to "exchange) a little air helps. Also using good quality cedar cigar boxes is very helpful. Not only are they good to help your sotred cigars mature, but Spanish Cedar (among other woods) can act as a humidity buffer keeping the moisture content from climbing up or going down too fast to affect the cigars.
Good luck & have fun.
