Spray the back of the pattern sheet with spray adhesive. I like to use Krylon #7010 All Purpose Spray Adhesive or 3M Spraymount. They have enough stickum to hold the pattern pieces in place but not so much that you can’t get them off afterwards.

Decide which side will be the inside of the bowl and stick your pattern to that side.

Cut the dish out and leave the paper on.

It’s time to score some lines. Lay your tinplate on your soft scoring surface. A piece of cardboard, like poster board or cereal-box cardboard, works well. Don’t try to use a hard surface like Formica or glass—you won’t be able to score deeply enough.

Align your straightedge parallel to one of the valley-fold dotted lines, so that the wheel of your glass cutter lands right on the line. Then run the glass cutter along the line, pressing hard. Do this three or four times, being careful not to move your straightedge. This should give you a deep score.
Now move the straightedge over to the next valley-fold line and repeat the process.

Turn the work 90° and go through the same process with both of the lines running the other direction.

The bottom side of your work should look like this.

With your awl, mark the outer ends of the little lines that run 45° in the corners. This is just so you can see the mark from the other side.

With your glass cutter, deeply score these short, corner mountain-fold lines from the bottom side of your dish.

Your corner should look like this.

Using the ends of the valley-fold lines from the other side as guides, score the mountain-fold lines for the outside tabs.

Remove the paper (it will come off in pieces) and clean the glue off your work with alcohol.

Now comes the fun part. The first thing to do is to fold over the tabs that form the top edges. This is best done by working just with your fingers from the top side. The tinplate will want to fold on the score line but it may need a little persuading. Try doing it over the sharp edge of a table. Don’t worry if the edge gets a little ripply—we’ll deal with that in a minute. Do all of the top tabs this way.

It may be helpful to press the tab against your work surface to help the bend along.

When all of the tabs have been bent over as well as you can bend them, turn the dish face up on your work bench and press the fold as flat as you can with your fingers. You should be able to get it pretty flat, but if you want it really flat, you can tap the edge with your small hammer (shown below) or squeeze it in your vise—it’s your call.

You should be able to get it pretty flat, but if you want it really flat, you can tap the edge with your small hammer (shown here) or squeeze it in your vise—it’s your call.

The next thing to do is to get the corners started. Just bend them with your fingers in the same direction that you scored them. Don’t try to bend them too far. At the same time, slightly bend the sides up a little—again, not too far. Do all of the corners this way.

If the corners aren’t sharp, you can use some flat-nose pliers to sharpen them.

Your piece should look like this.

Now you’re going to bring the sides up, which will bring the corners together. Start at one corner, gradually bending a side up as you go. Put pressure on the bottom of the dish, close to the score line, to help the metal know where to bend. Work your way around the dish, doing a little at a time. This may take two or three goes to get the sharp bends along the bottom edges that you need.

(Bending the sides up and bringing the corners together.)

(Refining the creases.)

You’re nearly there. When the sides are as high as you want them, all that’s left is to clean up any awkward bends that may have occurred, usually in the corners. You may want to use a small pair of pliers to help straighten the metal.

You can leave the corners open or you can close them up tightly, as you wish. Also, you can let the corner tabs project into the bowl at an angle or you can fold them flat against the sides.

You’re finished! Fill your bowl full of M&Ms and have a party!