David's Rules for Small Layouts
Part 3 of 3: Construction
Parts 1 and 2 covered mini- and micro-layout concepts and design. Now it's time to talk about materials and methods for construction. This is perhaps the most nebulous topic simply because there are countless ways to build a layout, so allow me to replace the term "rules" with "suggestions." You may have already been building layouts for some time and have your favorites, so you may elect to skip this part. But if you're a relative beginner, or if you're open to the possibility of new ideas, then please consider sticking around.
Materials
One of the basic precepts underpinning mini- and micro-layouts is (or logically ought to be) portability, and obviously this is improved as weight is reduced. Fortunately there are some interesting materials that are both rigid and lightweight, and hence ideal for our needs. Chief among them is my number-one go-to product of choice: Gatorfoam. Available in several thicknesses, it improves upon the concept of the perhaps more familiar Foamcore—which consists of a layer of foam laminated between two layers of heavy paper—by making the paper layers significantly more dense and water-resistant. Indeed, while Foamcore is not recommended as a layout base owing to a lack of rigidity and dimensional stability, particularly in high humidity conditions, Gatorfoam can successfully serve as the sole structural ingredient of many a small layout.
Another product I've frequently used is relatively familiar to modelers these days: foam insulation board. However, most modelers may think of it more as a scenery-building material, whereas I've used it as the sole structural ingredient of some small layouts. The choice between foam insulation board and Gatorfoam is mostly a function of how deep the finished terrain will be. For instance, if the layout setting is urban industrial, with virtually everything on a relatively flat plane, I'll go with Gatorfoam. If the setting is, say, a quarry in rugged terrain, I'll start with foam insulation.
But it's not an either-or situation; a few layouts I've built were relatively flat, but having some significant below-grade feature such as a river or a right-of-way through a deep cut. In these cases I've used both materials, essentially making a big sandwich of Gatorfoam and insulation board.
After having built over a dozen small layouts, I've also learned what not to use. Wood is just too darned heavy to begin with, requires heavier-duty tools, and makes a bigger mess. Both Gatorfoam and insulation board can be cut with utility knives and small hand saws. Particle board is worse than wood, having less rigidity and dimensional stability, especially under high moisture conditions. Foamcore is just too wimpy and, more importantly, suffers greatly when exposed to high humidity or direct contact with moisture.
This is not to say it's "my way or the highway." I've seen some handsome, relatively lightweight layouts constructed from luaun plywood and small dimensional lumber, as but one example. It's more of a matter of personal preference, skill set and familiarity. Not to mention cost: foam-based products can be more expensive than "traditional" materials. But I've found that added cost is often balanced out by lighter weight and reduced construction time. If you're willing to try new things, you may be pleasantly surprised by the results of my favorites.
As an aside, I've never seen Gatorfoam sold in a brick-and-mortar store (and don't confuse "ordinary" Foamcore—readily available at craft stores such as Michael's—for Gatorfoam). But it's readily available online. Some shops will custom-cut the material for you, which can be a benefit under certain circumstances (compare cutting fees with added shipping costs for larger sheets). Foam insulation board, by contrast, can be found at any home improvement store.
Let's Build Something
Which materials should be used under what circumstances? There are no hard-and-fast rules; every layout is different, after all. But there are some guidelines I can provide to help get you started. It's down to three factors: railroad grades, terrain elevations, and overall layout size.
If the railroad has no grades and the terrain is relatively flat, you can get by with just one or two layers of half-inch-thick Gatorfoam, depending on layout size. If it's around 18 by 24 inches or so, one layer is probably sufficient. For larger layouts, I'd laminate two layers together. The latter case gives you the option of including some small below-grade terrain details—say, a drainage ditch or a creek. The track can be laid directly on the surface of the Gatorfoam.
If the railroad has no grades but the terrain is irregular, layout size will dictate a choice between one or more layers of insulation board for layouts 18 by 24 inches or smaller, and a combination of insulation board and a layer of half-inch-thick Gatorfoam for the base for larger layouts. In either case, you may want to include an optional roadbed layer of quarter-inch-thick Gatorfoam, depending on the degree of "drama" the terrain presents.
If the railroad has grades, then follow the recommendations above, with the virtual necessity of a roadbed layer of quarter-inch-thick Gatorfoam. The material has the ability to create natural grade transitions, and it will provide 100% support for the track under all circumstances. Half-inch-thick Gatorfoam risers (or the equivalent) will be required.
An alternative to layers of insulation board for "dramatic" terrain would be assembling a box from half-inch-thick Gatorfoam, and supporting all of the roadbed with risers. This would be preferable if there will be significant sub-terrain infrastructure, such as complex wiring, below-grade switch machines, and so on. This will, naturally, increase the complexity of—and hence the accuracy required for assembling—the box. Based on experience, I'd also recommend using carpenter's glue for the assembly, as most of the joints will be edge-wise and require extra strength.
Cutting either of these materials is not particularly difficult. Gatorfoam can easily be cut with a utility knife: simply slice through the dense layer on one side, then bend and snap. Likewise for insulation board: cut through roughly half of its thickness, then bend and snap. Complex cuts are most easily made with a jigsaw; I use a small battery-powered unit. A "flush cut" blade (which has smooth sides) is recommended for cleaner cutting. As an alternative, Gatorfoam can be cut in any shape with a utility knife using two or three firm passes. Insulation board is a bit more challenging, but can still be managed with a smaller (narrower blade) packing knife. Of course, insulation board can be cut cleanly and quickly with a hot-wire tool, if you're so equipped.
Adhesives
Success with certain construction materials will benefit from the use of certain adhesives. Now, before anyone accuses me of being a shill for a manufacturer, particularly the Henkel Corporation (makers of Loctite products), I most assuredly am not; I've simply found, after many years of trying many different products, that certain adhesives prove to be superior to others. There are, of course, alternatives—there always will be—but I'm not going to waste bandwidth by citing all possibilities. If you regularly use adhesives, and know what's most appropriate for a given task, then it's likely you already have some favorites.
When laminating sheets of foam insulation board, or when bonding Gatorfoam to insulation board, I'll use Loctite Power-Grab. It's available in squeeze tubes as well as caulking gun cartridges. It has a very aggressive tack, and holds parts together quite well almost instantly, although curing overnight under some heavy books is always recommended. Incidentally, one not need cover all of the surfaces to be bonded. A thick bead along the edges, plus a big "X" through the middle, is sufficient.
When laminating sheets of Gatorfoam—for instance, to make a base for a layout larger than around 18 by 24 inches—I'll use Loctite heavy-duty spray adhesive. It works much like traditional contact cement (which would serve as a substitute): spray both surfaces to be bonded, allow them to set for a minute or two, then press them together. Just be careful: parts will not be repositionable.
When bonding Gatorfoam risers in place to support a roadbed layer, I'll use Titebond III Wood Glue. Plain old white glue would do in a pinch, but Titebond is waterproof, so things won't come undone by, say, ballasting or plaster scenery.
When laminating relatively small pieces of Gatorfoam—say, assembling a few strips to support a portion of roadbed—I'll use Loctite Professional Liquid Super Glue. In less than a minute the joint will be as strong as if it was solid material.
Some other tricks I use may surprise you. When bonding layers together, sometimes it's not convenient to apply weights while the adhesive cures due to multiple levels, tight contours or whatever. Believe it or not, long decking screws work really well at holding layers of insulation board together. They're also an excellent supplement when bonding Gatorfoam to insulation board. Just be gentle—obviously it's not wood!
Tracklaying and Suchlike
Laying track on (perhaps) unfamiliar materials may require (perhaps) unorthodox methods—some of which may surprise you. I have two favorite methods, depending on the track and roadbed types.
To bond roadbed track, such as Kato Unitrack or Tomix Fine Track, to Gatorfoam, I'll simply hold the track in place and run a small bead of Loctite Super Glue down each side of the track; after a few seconds, the track won't be going anywhere. To bond roadbed track to foam insulation board, I'll apply Loctite Power-Grab to the underside outer edges of the track, press it in place, then apply weights until the adhesive cures.
To bond non-roadbed track to any type of base, I'll use 1/8th-inch-thick double-stick foam tape. If you buy the tape from a store (it's available in small rolls at craft and home improvement stores), this can get rather expensive; I recommend buying a large roll online. The cost may seem steep, but once you try it, you may not want to lay track any other way afterward. One little tip: you'll need to remove the top release layer to bend the tape along tight curves, and re-apply it until you're ready to attach the track. And now, one word of caution: there's virtually no margin for error when positioning the track. Therefore, practice is strongly recommended before doing the real deal.
I'll follow similar rules when attaching other items to a layout base. Styrene streets, building foundations and the like will readily bond to Gatorfoam using super glue. When attaching the same items to insulation board, I'll use either Power Grab or double-stick tape. Scenery materials such as Sculptamold (my personal favorite) can be applied to almost anything, while insulation board may need to be roughened up to enhance bonds with materials such as ordinary plaster. Chemically-based adhesives such as super glue and other substances like lacquer paints should never be used directly on insulation board, as they can damage or even completely dissolve it.
Finishing Touches
One good way to be taken seriously is to be serious about your modeling, and this includes finishing touches. I apply a layer of Foamcore or other thin material to the edges of a layout, then apply some sort of laminate, such as self-adhesive woodgrain vinyl (e.g., Contact). For some special projects, I may go full-bore and adhere real wood veneer. I'll even go so far as to finish the underside, and attach felt feet. While this may sound somewhat "anal," it serves multiple purposes. The feet protect both the layout and the surface of whatever it may be placed upon, while the laminate shields the underside of the layout from moisture as well as wear and tear.
Skilled modelers will admire the effort, but even lay people will experience a subconscious sense of professionalism. I've known modelers who could not care less about non-model surfaces, such as edges and undersides, and while it's their layout and their prerogative, I also know (especially after a few decades in marketing) that appearances do count. Unfinished surfaces detract from the important stuff—that is, the modeling, whereas finished surfaces subtly tell the eye where to focus.
Go Forth and Be Creative
I didn't get where I am today by following anybody else's rules, so who's to say you need to follow mine? My only final word is that I've tried an awful lot of stuff, so I do speak from some experience. But there will always be new materials, new techniques and new ideas to come in the future, so by all means try different things! It's the best way to learn.