Since we have started offering blocks of Polyurethane foam on the website, we thought it might be useful to offer a demonstration of how it can be used to create unique diorama bases for your figures and vehicles. Creating a base doesn't have to be difficult or even time consuming as this article will demonstrate. It helps to have certain tools but specialized tools are really not necessary as the foam is very easy to cut, carve and sand.
The idea of offering this foam stemmed from requests for us to produce larger diorama bases than what we typically like to create. To explain a little bit about why we haven't offered larger bases so far, there are a few considerations involved.
If you imagine a larger resin cast base that might measure 11"x17" or more, the decision has to be made about whether it would be cost effective to mold and cast, the weight and cost of shipping a larger piece and subsequent box and packaging costs, as well as the space it takes to accommodate inventory as orders come in. As we were able to acquire the foam in a small quantity, it made sense that some customers may want to try their hand at creating a diorama base as they envision it, without waiting for Monroe Perdu. Because of the light weight and large size of the block of foam, it is an economical alternative and even more so as our project uses only half of a block. In fact, if you emulate this project, you can cut the foam along the angled line with a hand saw and get as many as four bases like our project out of one block. The foam is referrred to as 2lb. density, meaning that it is very easily dented and abraded. It's good for creating landscape features and requires a light touch.
This is also a good opportunity to talk a little about process and approach to scratch building things, using tools that are not specifically model related.
We're spoiled to a degree in that we have an inexpensive bandsaw to make quick work of cutting out the oval shape. Realizing that not everyone might want to afford "shop" tools, a machine like this can be found for certainly less than $100.00 and along with a disc sander for about the same price, a vast amount of scratch building projects can be undertaken by those so inclined.
The bandsaw is in a garage area, in a place where a mess can be made but regardless, as you work with the foam, you will need a place where you can make some dust, not somewhere inside the house or apartment.
Now to describe the process...
The project starts by tracing the shape of the base onto the foam. In this case, it was an oval from our Corner Wall kit. I used a hard lead pencil to trace the shape and cut the foam with the bandsaw. The photos show the amount of the original block that was used. If your cut line is a little rough looking, you can sand the side of the oval to clean it up. A pliable sanding sponge works better than stiff sandpaper for this.
A paper strip was cut at an angle and was taped to the side of the oval. I used graph paper and just made sure I cut the angle at less than the height of the oval. I traced along the top of the angle with the pencil and flipped the paper over to make the same line on the other side. I drew a line across the top of the oval connecting the lines along each side.
If you don't have a bandsaw, the shape can be cut easily with a serrated kitchen knife. The trick will be to keep the knife at the right angle as you cut along the line. You can also cut just outside of the pencil line and then sand to the line.
The next part of the process is to use an x-acto or scalpel blade at a right angle to the side of the base and score along the pencil line. The blade doesn't have to cut very deep, perhaps 1/8" to 1/4".
Follow this step by cutting into the line from above at about a 45° angle. This doesn't have to be deep or exact. Pop out the sliver of foam with the knife blade and it should look like the photo.
This serves two purposes.
1.You are creating a "stop" line for your carving while releiving stress along the edge. This will assure that you won't fracture the edge of the piece and have s chunk break off as you carve and sand. This is going to be very important if you decide to create a peice that is square or rectangular and therefore has corners.
2. You now have a line to carve and sand to, all around the base that tells you when to stop carving.
I didn't bother to cut along the line across the top of the base as I was just going to start my scraping there.
Now it's a matter of removing the foam you don't want. As the photo shows, if my bandsaw were bigger, I could have just cut along the angled line and had two similar bases right away. Instead, this is a good project for using the "Sur-Form" tool to scrape the foam away. This is an inexpensive tool available at any hardware store. I think this cost me about $6.00. It works like a cheese grater and I sat over a waste basket and let the foam fall into it as I went. The dust wasn't much of a problem with this method.
The last photo shows the carving underway and the idea is to carve from one line to another to create the angle.
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