For an elementary school literacy night program, I was asked to create one of the props for the faerie tale themed event. Specifically they wanted a “head through hole” Cinderella’s pumpkin coach that kids could have their pictures taken in.
I always like a creative challenge, so I accepted the task and went to work. I had to start the project on a sloped area of lawn because I have no garage or paved driveway. After a short time, it began to rain, so I had to move the operation into a small dog kennel which kept the rain–with the exception of the random drip here and there–off the materials I was gluing and painting. The conditions were not ideal, but it is how I am used to working and it really wasn’t so bad.
I could have used plywood or even corrugated cardboard for the main part of the carriage, but I chose instead to go with extruded polystyrene (rigid foam insulation). This is a material used to insulate walls, and it can be found in some home improvement stores. Our Home Depot carries it, but Lowe’s does not. The main advantages of working with this material are that it is lightweight, it comes in a 2-inch thickness so it is easy to give it some dimension, and it is soft enough to easily carve to the desired shapes. But polystyrene does come with a list of disadvantages as well. It is fragile, painting takes some special considerations, the carving can get a little (or maybe a lot) messy and it isn’t exactly cheap. You will most likely have to buy a full 4-foot by 8-foot sheet. But a single sheet should be enough to complete a moderately sized project.
CUTTING FOAM BOARD
A large sharp knife works okay for cutting foam board, but it takes some pressure, and that can make it a little dangerous. I still have all my fingers, but I always try to keep in mind where the knife is going to go if I slip, and how my fingers are positioned to support the foam. I have cut rigid foam this way on several projects before.
This time, however, I tried using a reciprocating saw. It made the work easier, less messy and more precise, but there a couple things you may need to do for this to work well. First is to find a way to clamp or secure your board. The reciprocating saw take two hands to handle, so you can’t hold your board steady at the same time you are cutting it. The second thing is that the shoe of the saw will be pounding down upon the surface of the board with enough force to scar the area around the cut. If you lift the saw just a bit, the shoe won’t make contact with the board.
If you end up doing a lot of foam cutting, you might think about tools that are made for cutting foam board such as a hot knife of hot wire bow cutter. These tools cut with precision and virtually eliminate the mess.
GLUING FOAM BOARD
When I need to glue foam board pieces together, I like to use an Expandable Foam Filler-Adhesive. A large can of “Great Stuff” runs about $5 at home improvement stores. Like the board itself, this type of adhesive comes with some strengths and weaknesses. On the positive side, it is a very strong adhesive and will stick to almost anything (though a light sanding of the two surfaces before gluing can give it an even stronger bond). Texturally it is a very similar material to the foam board itself, so it can also be used to build up some raised areas on the surface of the board, it dries in as little as 15 minutes and it can be cut, sanded and painted in the same way as the polystyrene.
The problems with using expandable foam filler as an adhesive is that since it is such a strong glue it can be rather messy when it gets on surfaces you don’t want it to be on. It can ruin clothing and will stick to your skin for several days before it wears off. Wearing latex gloves would be a smart idea, but is something I rarely do myself. Also, the material expands to several times its original volume, so care must be taken to clamp the pieces together or use weights to keep surfaces from separating during the curing process.
The one area that I have not covered is painting. This is a crucial step to building a successful project, and this is the point at which everything comes together visually. Most rigid foam projects would look kind of silly if you just left them pink (or blue). Painting brings out the detail of the objects and gives them depth, texture and richness. If you don’t consider yourself to have an artistic flair, don’t worry. It usually doesn’t require a great deal of skill to create some wonderful painting effects.
However, there are some important things to know before you do any painting. Since I have already covered this subject in another article, am going to refer you to the painting section of Building a Faux Campfire. I strongly recommend that you look this over before you attempt to begin painting, to keep you from having to learn some of the hard lessons which I had to with some of my earlier attempts. This article also goes into greater detail about rigid foam itself, as well as some other issues that might be helpful to you.
I am rather confident that nobody reading this article will be constructing a coach for Cinderella. But when you do start a project–whatever it may be–rigid foam insulation may be just the right material to get the job done.