Well, maybe not a cake--more like a hot pink puffed rice cookie...Anyway, here's a nice way to make a mould for any pourable confection that doesn't require baking.

Step 1: Draw Your Footprint.

If you have a computer file, print it out. If you want to draw freehand, do it. I wanted to use the MAKE Magazine logo to celebrate our first birthday, and decided to try drawing it freehand.

I used a waxed paper box as the basis for my line width. I had the logo on a magazine cover as reference, and used a ruler to help me judge the width and height of each letter in reference to each other letter. It's not a perfect rendition, but it's pretty close.

Step 2: Make the Walls of the Mould.

Using the letters (or images) you've drawn as a footprint, make walls to support the material you're pouring in (in my case, rice crispy treat batter). I used the walls of the pizza box, but any long strip of cardboard will do. You will want to make sure the strips are even in height, and that the corrugation of the cardboard is vertical for horizontal strips. This makes it easy to bend your pieces to fit around curves--each bit of corrugation will bend in the right direction. If your corrugation goes the long way, then your bends will be hard to keep straight.

Tape the long pieces of cardboard together if each individual piece is not long enough for the footprint shape, and tape down to the footprint on the outside for stability.

Step 3: Grease the Mould.

Butter (or margarine) probably works best as it won't soak through the cardboard. This keeps the rice crispy treat batter from sticking and makes removing the mould easy.

Step 4: Start to Make the Puffed Rice Treat.

Make sure to calculate how much you will need to fill the letters--you will need more than you think. I assumed that doubling the standard recipe would be more than enough (that's enough to fill two 9x13 inch casserole dishes), but it barely filled in my mould.

For this recipe (doubled from the one on the marshmallow bag):
4 T butter
2 bags marshmallows
12 cups puffed rice/Rice Krispies

Melt the butter and add the marshmallows over medium heat. In a separate bowl, measure out your puffed rice.

Step 5: Add Food Coloring (if Desired).

Since the MAKE logo is red, I decided to add some food coloring.

Actually, make that a lot. Add until the desired color is reached.

Step 6: Add the Puffed Rice to the Marshmallow Goo.

Stir until well mixed.

Step 7: Pour Batter Into the Mould.

In this case, the batter is pretty stiff, so you have to really pick it up with your hands and press into the shape. Be careful, as melted marshmallow can be pretty damn hot.

Step 8: Let the Batter Harden.

It probably only takes an hour or so, but I left mine overnight. When the cookie is cool and doesn't yield to the touch, it's ready to be taken out of the mould.