A build-your-own s'mores kit, with homemade graham crackers and marshmallows, all packed into a convenient tin!

Marshmallow turns out to be pretty easy to make. You cook a water/sugar/corn syrup mixture to the firm ball stage (240°F or so), and then whisk on high speed with a mixer until it thickens. Pour the result into a pan and it will become marshmallow texture once it cools. Then it can be sliced into graham cracker-sized rectangles. Any stickiness can be subdued by dusting with a 50/50 mixture of powdered sugar and corn starch.

Note: When I took the photos below, I did not have any marshmallows, so an index card fills in as a placeholder.

Making the graham crackers involved a little more ingenuity. It also required, among other standard ingredients, graham flour which I was surprised to find is readily available at grocery stores. I really liked Joe Pastry's recipe, although I used graham flour rather than the mixture of whole wheat and rye indicated. The graham crackers are flavorful without being overpowering, and have a nice crispy texture.

From there, I needed two 3D printed objects to assist with the process. First, a simple trick for ensuring consistent uniformity of the rolled dough: rolling pin rings! I simply modeled these with a hollow cylinder of the correct dimensions to slide snugly over the edges of a rolling pin. The rings are 1/8" thick and I printed two, one for each side. These ensured I could consistently roll out a perfectly-even slab of graham cracker dough.

The final item on the agenda was a cutter. The model for this looks a bit strange. One reason is that it's actually half of a cutter, because the build plate of the 3D printer isn't big enough to fit a 2.5" x 5" object. So along one edge of the cutter are the perforations that wind up in the middle of the cracker. I had to reverse the direction of the cutter for each pressing. The spikes are there to provide docking (the small holes speckling the surface, which make it bake flatter).

I call it a "cutter", but it's really just for making an impression. Pushing hard enough to cut all the way through would get it stuck in the dough, with the support structures imprinting themselves as well. It was sufficient to lightly press the cutter into the dough, just enough to create score marks. The rectangles could easily be snapped apart once the baked crackers had cooled.

In the end, I thought it worked really well! The graham crackers looked practically factory-made, and tasted delicious. And they fit perfectly in the tin liners, alongside some chocolate squares and the marshmallow cubes.