
One common question I've been asked is how to make the clay stick to the metal surface of the box. Perhaps you need to develop a strong dislike to strong mints. ;-)
Actually, I think it helps. When I started covering these boxes, I didn't handle the boxes that much because I didn't eat the mints. After tearing off the shrink-wrap, I immediately dumped out all the mints and washed the empty boxes in hot soapy water to remove the powdery residue. Then I carefully dried the boxes and immediately covered them with clay.
If you have Altoid boxes that have been frequently handled (picked up, opened, closed, etc.), they're likely covered in just enough hand oils, powdery residue, dust and dirt to make it difficult for the clay to stick well. I'll bet if you clean the boxes and your hands before covering the boxes, you'll have no trouble making the clay stick.
The other critical aspects to assuring the clay sticks to the box surface is to make the cover fit like a glove and remove any trapped air. I think it also helps to use clay that is as soft as Premo. Softer clay tends to stick better to itself and anything else it touches.
Here are the steps to cover a standard sized Altoid mints hinged lid box.
Supply list:

Instructions:
1) Cut a couple of sheets of waxed paper that are approximately 6" X 6" each. Precision isn't important, though. Set aside.
2) Covering the Altoid box bottom:

As you place the clay sheet on the tin, gently stroke the sheet onto the clean metal surface, advancing from one edge to the other. By gradually covering the surface like this, you reduce the chance of trapping air under the clay.
Roll across the sheet using your Lucite roller. This seems to really help the clay stick to the metal surface and also reveal any trapped air pockets.
If the clay sheet
tends to stick to the roller, place a sheet of waxed paper on
the clay sheet and roll over the waxed paper.
Remove the waxed paper.
Check for air pockets
(gently raised domes in the clay). If there are any air
pockets, it's too late to pry the sheet off because it seems
to stick to the clean metal surface pretty well. Use the
thinnest needle you can find to poke a hole in the pocket and
push to force out the air.
Re-roll to smooth the surface. Gently press the hole with one of your fingers to close it up.
Re-cover the clay sheet with the
waxed paper. Flip the box so it is right side up. Place the
box on your work surface.
Trim away the excess clay using your NuBlade. By setting the clay covered surface on the wax paper, you prevent your piece from sticking to the work surface.

As you place the clay sheet on the box, gently stroke the sheet onto the clean metal surface, advancing from one edge to the other.
Finish using the same covering technique you used to cover the bottom of the box.
Cut away the excess clay by flipping the box upside down and trimming. If you've left the box bottom covered by wax paper, temporarily remove it so you can easily trim the top sheet.

4) Covering the lower
sides of the Altoid box:



Place waxed paper on the
box top, then flip so the box is upside down. 
7) Adding ball feet:
Use the 3/16ths inch hole
punch to punch out eight (8) circles out of a clay sheet that
is #4 thick. Combine four (4) of the circles into one ball.
Combine the other 4 circles into another ball.
Repeat this process three times, punching out six (6) circles to make two balls, then four (4) circles to make two balls, and finally two (2) circles to make two balls. You should have a total of eight (8) balls of gradually decreasing sizes.
Arrange the balls on both sides of the center ball. Make sure they rest along the trim sides as well as the bottom.

Obviously, you can decorate as you like, and you can get far
more detailed, adding different shapes, different trim, etc.
Be creative and experiment.
Use the Xacto knife with a #11 blade to score along either side. Use the #19 blade again to cut upwards along the hinge itself.
If the clay is firm enough, you can easily remove two little slots which will allow the hinges to work as soon as the box cools from its baking. If the clay is very soft and distorts easily, scoring the slots will suffice. Wait until after baking and cooling to finish removing the clay from the slots so the hinges can work.
"What are the tweezers for?" you may wonder. If your workspace and home are like mine, you've got no better way to deftly remove those sneaky little cats hairs that seem intent on attaching to the raw clay. ;-)
10) Baking:

11) Sanding and Varnishing:

