There is a ton of styrofoam in this packaging and I saved it all. The type I am upcycling is called EPS or expanded polystyrene which doesn't break down over time making it very hard to tip in the trash or recycling bin.
I noticed that some of these companies are using small cardboard L's to get around using a lot of styrofoam and these bits are going to be the tip-top of these projects.
Other handy bits found in packing are pieces of wood or particle board cast off the from manufacturing process. While heavy, it does fill space in a shipping box nicely. I have my cutting mat sitting on one, just so you don't think my table is a strange two-grained surface.
I have my styrofoam and a couple of cardboard Ls on the cutting mat, plus Sarafina the Cat for scale.
You will need your tool kit, styrofoam pieces, cardboard, heavyweight paper, and maybe some other items particular for your build, like popsicle sticks or stir sticks.
What scale am I using? I call it "handy scale". Pieces are bigger than an inch and beyond that, I don't care much. I have both 15mm and 25 mm figures. I want the display pieces to be big enough to look nice but small enough to move around and store easily. I want to be able to use them for both 15 and 25 mm figures.
I can set these parts to a scale like 1" equals 6 feet. In this case, the cardboard L is two inches wide (12 feet) and one inch high (6 feet).
As I mentioned, the cardboard Ls are going to be the cherry on top of this project. They will be both the roof and a ready-made item I don't have to cut.
Each small L is about 4 to 5 inches long. The foam needs to be cut just a smidgen smaller than that, say 1/2 inch smaller so the overhang is close to the same all the way around.
The trick is to move swiftly and smoothly as the wire radiates heat which melts the foam some distance from the contact point. This takes practice and the jig or template can help. Assuming you make it correctly, unlike me.