Editor's Note: Pictures coming very soon!
Foamcore (also known as Foamboard) is a common and useful product for a variety of light construction projects. It's lightweight, fairly strong, and easy to find. However, it warps when wet, permanently creases when folded and can be difficult to cut properly. However, once you understand how to work with the material, you can create some excellent terrain features quickly and without too much effort. This article is intended to give you the basics of using foamcore rather than show you how to build something specific (that's for another tutorial!).
I have used foamcore to build scenery for years, and the recent release of Cities of Death convinced me and a friend to embark on a major project. $50 and 40 hours of work (between us) later, we had more than a dozen buildings, enough for a Cities of Death Gamma game with extras to rotate through.
What you will need:
This is a list of items I have found useful in working with foamcore. All you really need is a blade, glue and an idea, but adding a few more items to the list improves the end results considerably. I'm sure there are a hundred other tools that are useful, and if you have a critical one I missed, let me know!
Hobby Knife (beginner):
The ubiquitous tool of the modelling trade, and the number one item on the list. For foamcore, you want to have one you can replace the blade on. Most handles are compatible with Xacto blades, which is critical since foamcore dulls blades like crazy. I use both #10 curved and #11 classic straight blades. Keep a supply on hand for swapping.
Straight Edge (beginner):
This is as critical as the blade. Cutting a straight line through a material as resistant as foamcore is tough without one. I use both a yardstick (for very long cuts) and an 18" metal ruler with a corked back for shorter cuts (the cork keeps it from sliding).
PVA/Wood Glue (beginner):
Classic Elmer's Glues, necessary for sticking things together and for sealing foamcore prior to painting. Almost any form of this will work (don't use glue sticks!).
Drafting Kit (beginner):
This the best term I have to describe the kit. There are $5 kits that contain all you will need - a 45 triangle, a 30/60/90 triangle, compass, protractor, and other small tools. The cheap kit has everything you will need, and believe me when I say you want this for checking angles and drawing out patterns prior to cutting. it may also contain a french curve.
Hot Glue Gun
Hot glue gun (beginner/intermediate):
Not necessary, but frustrating angles and hidden corners can be made virtually indestructible by using hot glue. It's also very cheap.
Cutting mat (beginner/intermediate):
A self-healing mat would be best as it saves blade edges, but any surface you dont mind cutting up will be fine. You may want a large mat, since many of the cuts you will make will be long.
Seamstress pins (Beginner/intermediate):
The greatest discovery in working with foamcore. Pins help hold glued corners together, allow you to fit pieces together without gluing or other adhesives like bluetac, and the proper sorts of pins (flat head) look like rivets. Pin holes can be covered with paint or detailing strips, and pins can be left in the finished product for strength since they look like rivets.
Circle Cutter (intermediate/advanced):
A circle cutter isn't required for building with foamcore, but it's very good to have. Cutting a good looking circle without it is almost impossible.
Angle Cutter (intermediate/advanced):
A tool for making 45 degree beveled edges for corners. Again, not required, but if you want to avoid having some exposed edges of foamcore to cover on corners, you will want one of these. Xacto makes one that also does channel cuts.
Balsa Stripper (advanced):
Commonly for cutting strips of Balsa for airplane models, it is great for cutting the edging strips from cardstock and for cutting strips of foamcore for detailing work.
There are 2 thicknesses of foamcore commonly found; 3/16" and 1/2". The thicker stuff is best for exterior factory or bunker walls. It's harder to cut and less useful than 3/16", in my opinion. Glossy cardstock, such as GW boxes, is important to have on hand for covering the edges of foamcore and for surface detailing, as is plasticard. You can include a lot of other items in this list, but for basic work, all you need is the foamcore and cardstock.
Cutting Straight Lines
Cutting Straight Lines:
Draw the line first on the foamcore with a fine line pen, being careful not to press hard enough to mar the surface. Align your straight edge with the line, and use the straight edge as a guide for each cut - it allows you to concentrate on the angle of the blade and make the cut faster and smoother. You're going to make this cut three times, so make sure you've got everything stabilized. Using a #10 curved blade, start with the point and apply light pressure as you start, keeping the handle aligned with the line you are cutting. The first cut should go through the upper paper surface but do not apply too much pressure. Tilt the handle of the blade as you cut, distributing the cutting work over as much of the blade surface as you can. Repeat the cut, this time with enough pressure to get through the foam. A final cut will go through the paper on the other side. Be sure you apply enough pressure on the final cut to get through the paper - it is the most difficult cut to make cleanly.
(I'll post pics of each stage of the cut here)
Cutting a Curve
Cutting a Curve:
Curves are vicious things to cut in foamcore, requiring a very steady hand and some patience. If you have a french curve, you can use it to guide the cut. Otherwise, you're on your own. Use the #11 straight blade for these cuts, and follow the same procedure as before, being very careful to keep the blade aligned vertically. Make sure you have a good line to follow before you start cutting; paint can cover up excess lines, but there's not much we can do to cover up bad cuts.
There are 3 common mistakes when working with foamcore; using too much pressure, angling the blade unintentionally, and using a dull blade. I'd like to note at this point that regardless of whether you're cutting on a curve or straight line, it's important to concentrate and pay attention to the cut. Foamcore has a tendency to pull the blade off center, and where that straight cut was going perfectly, it will unexpectedly veer or pull, leaving you with a wavy or curved cut which is difficult to correct.
Using too much pressure usually results in creased or folded edges on the cut. This will have a negative effect on the final product, and the ferrule may even tear the upper paper surface. Use mulitple cuts to get through the foam every time and you will avoid this issue.(picture coming soon)
Angling the blade unintentionally is very common. That straight line cut you made followed the line perfectly, but the results are wobbly. Being attentive to the angle you hold the blade and cutting at a slow pace will resolve this. (picture coming soon)
The dull blade will ruin a project easily. If the paper or foam look ripped up or torn despite your efforts to be careful, the blade is at fault. Replace it and try again - you'll feel the difference. (picture coming soon)
Exposed edges of foamcore have an undesirable look, and should be covered. Glossy cardstock can be used to cover almost any edge. You'll want to have a precut stock of card to work with, so slice up some strips the width of the foamcore you are using (3/16" in most cases). These need to be perfectly straight to be useful, so be careful when prepping. Use full strength PVA or wood glue and cover the edges, making sure to trim all corners to look nice.
While plain white might work for some people, you'll undoubtedly want to paint your project. Unfortunately, foamcore is susceptible to water damage, and you can probably guess what acrylic paint will do. Unfortunately, PVA is also water based. Luckily, we can thin PVA slightly using other non-water products (Future floor finish works for this) and keep from warping and ruining the project. Using an old brush, apply a thin coat of thinned PVA (2:1 glue to thinner works) over the surface. Do small patches at a time; this avoids warping. Seal all surfaces and edges completely. Once sealed, basecoat and paint as normal. Spray paint can be used, but only if you are absolutely sure you sealed the piece thoroughly. The PVA seal will add a little texture to the surface; add additional surficants to your paint, like fine grit or sand, to make the effect more uniform and building-like. If the paper separates from the foam, too much liquid got to it and the piece has failed; you're back to square one.
Flat surfaces are nice, but raised and varied surfaces really make buildings pop. Adding cut strips of foamcore, detail bits of plasticard and surface details of cardstock will all bring extra detail and quality to the finished product. Again, be careful to seal the piece before trying to laminate card to it, and use only as much glue as you need. Excess moisture will ruin it, and it would be a pity to ruin a piece this far into the process. For more details on this, check out the building tutorial. (will be linked)
I hope you have found this to be useful. While this doesn't detail all the processes of building a structure, it gives you the basics you will need to use foamcore effectively. I'll post an example building tutorial in conjunction with this once I have it completed.
Of course, C&C welcome, and if you have a tip I've not listed let me know!