There are many ways to make a Copenhagen solar cooker. Here you'll find two variations, both of which are designed to be disassembled for maximum portability. The variations differ in how the base is made. The reflectors are pretty much the same.
All you need are four 14 inch x 14 inch flexible reflectors, an 8 inch x 8 inch base and some clips to hold the tops of adjacent reflectors together.
Making the reflectorsThe reflectors can be poster board (thin cardboard) or vinyl or anything flexible enough but not so flexible that they droop down or flop around in the wind. I've considered using plastic placemats except the ones I know of are all 12" wide whereas I need at least 14". The reflective covering can be aluminum foil or reflective/aluminized mylar. The base can be wood or cardboard; it must be able to handle heat.
For some unknown reason the orange poster board is thinner than the blue one and gets almost too soft with the glue I used. So get the thicker poster board when you buy it.
The glue I was using was just normal white school glue found in any store that has a school or craft supply section. Since it takes 24 hours to dry completely I put stacks of heavy books on them overnight.
Some important tips: I first tried putting the glue on the poster board and that resulted in bubbles and poor gluing of the aluminum, so I subsequently applied the glue to the aluminum foil as in the above photos. Also, the glue softened up the orange poster board, even if I put the glue on the aluminum foil. It seems the orange poster board is thinner than the green or blue and this caused the problem. So when shopping for poster board, select the thickest ones.
I also put tape all around the edges to protect the edges.
Making the base
The base is what will hold the reflectors in place at the bottom. It's also what the hot cooking pot will sit on, unless you put some sort of stand between them. It should be made of something that won't melt, so plastic is a bad idea. Melting can happen due to the hot cooking pot and also some sunlight reflected onto it. I used corrugated cardboard from old boxes. Wood is also fine. Keep in mind that for maximum portablity you want to be able detach the reflectors from the base for when not in use.
I've made two different types of base:
Both are documented below.
Making the corner attachment type of base
This method attaches the reflectors to the base at the four corners of the base using things like twist ties or shoelaces. It requires making holes in the base and corresponding holes in each reflector. This method was invented by Sharon Clausson who is the inventor of the Copenhagen solar cooker.
Cut out a piece of corrugated cardboard from a cardboard box. Make it 8 inches by 8 inches. Glue an 8 inch by 8 inch piece of aluminum foil to one side.
Following the photos below:
After you've removed the nails, you should have eight holes in the base and two holes in each reflector. These holes need to be enlarged to fit the twist ties or the shoelace you're going to use. To do that I stick the blade of an xacto knife in each hole and twist the knife while pushing on it gently, as shown in the following photos.
The next step is to assemble it all. For that see the Assembling the attachment type subsection on the main Copenhagen solar cooker page.
Making the slotted type of base
This method attaches the reflectors to the base by having the reflectors slide into slots in the base. The reflectors may slip out of the slots a bit when you adjust the them during use. This can be fixed with additional securing mechanisms or by adding paper to make the fit in the slots tighter as needed. This method was invented by Teong Tan (a member of the Yahoo SolarCooking group).
Take two 8 inch by 8 inch pieces of corrugated cardboard, draw diagonal lines on them from corner to corner and sew them together long those lines. That leaves the four sides open for wedging the reflectors into (see photos in assembly section below.) Make sure you sew them together tightly so you have a snug fit. If the fit becomes loose then you can stuff wedges of paper in to make it snug. I added the innovation of cutting a hole in each side of the bottom piece to make it easier to find where to push the reflector into.
To sew them together I used 30 gauge bare copper wire which I just happened to have a lot of. Since it's the same thickness as thick sewing thread, I was able to use a normal sewing needle. You can use string or whatever won't melt (plastic fishing line would melt.)
The top piece is then covered in aluminum foil to help with solar reflection and for some heat protection.
The next step is to assemble it all. For that see the Assembling the slotted based type subsection on the main Copenhagen solar cooker page.