Basic architectural models in ‘Kraft board’

I am about to do some sessions in basic model-making for 3rd year architecture students at London South Bank University. What follows is a version of the session notes together with photos of the practical examples, and some step-by-step demonstrations of how to work with the material. This is intended as a point of reference for the students afterwards and it may repeat information given elsewhere on this site.

Models are by default ‘looked down upon’ because of their size! They can provide an instant overview, with the precision of a groundplan in three dimensions .. they flatter us with a ‘god’s eye view’, and one needs to be reminded that this viewpoint is an artificial one. For example in theatre design this is can lead to design problems .. at normal table height the designer working on the model has an Upper Circle view of the stage most of the time. But in architecture one could argue that viewpoint is less of a consideration anyway, because in this context models are never meant to be realistic simulations and it would in any case require an impossibly huge model to reproduce anything like a pedestrian’s experience of the building. For reproducing these impressions, and to preview and rehearse the organization of interiors, digital simulation may be far better suited. But even though our relationship with the card model is very removed from the one we would have with the real building, it’s also very direct .. because of its real physicality. It’s made of material .. just as we are. It needs to be handled with care because it’s vulnerable. It responds to changes of light through the window or to the shadows cast by people moving around it. It’s physicality can even be enhanced by imperfections, to a certain degree, because we’ve come to expect them in physical things.

For the first session I’ve chosen to focus on working almost entirely with ‘Kraft board’, which I feel is a very honest, unpretentious and direct material. As I’ve implied my emphasis is also on small-scale ‘massing’ models, concentrating on essential form rather than detail, serving as preliminary or idea-development models within the process. These models are more than private sketches .. they are meant to present the status of ideas so far, to communicate them to others in a clear, controlled and deliberate way. The keyword here is deliberate! Although the work may still be in progress and not yet finalised, the statements made by the model should look valued, cared for, sufficiently thought about .. in other words, deliberated. On the other hand, there should still be a feeling of ‘sketch’ .. using a fine material for this would impose a false sense of finality. So the object is to achieve a model which looks presentable and reasonably sure of itself, but also still open to discussion and without having cost a lot of time, money or effort. ‘Kraft board’ lends itself very well in this respect, because although it is structurally very strong and easy to cut cleanly, surfaces and edges retain a typically raw and recycled look. Cut edges cannot be made to look 100% smooth and detail is difficult beyond a certain level .. both of which can actually support the general aim.

architectural model

I’m assuming you probably don’t know what I mean by ‘Kraft board’. It’s unlikely that you do, because it’s the name given by the one supplier I know, Seawhite of Brighton, to a very thin form of brown, recycled cardboard which is made up of thin layers and corrugated on the inside. The outside is smooth and firm, but matt and untreated (different from the usual, thicker form of corrugated cardboard used universally, which has a very slight sheen). In the packaging industry card which is composed of one corrugated layer enclosed within a surface layer on both sides is known as single wall board and one of the thinnest is made to a 1/16th of an inch. I’m guessing this is the ‘Kraft board’ that’s available from Seawhite because this is, as close as I can measure, a little under 2mm. I had thought that the name was just a quaint variation on ‘craft’ implying that the board was for general-purpose creative uses, but it turns out that the ‘Kraft process’ is the name of an established method of wood-pulping which produces a particularly tough paper and ‘Kraft’, given by the German inventor of the process, denotes ‘strength’.

Kraft board

The main characteristics of ‘Kraft board’

In the first place it is one of the cheapest forms of card I’ve found. At University of the Arts London shops it costs £1.15 for an A1 sheet. Seawhite only normally supplies wholesale but they have a selling website where a box of 25 A1 sheets will cost £24.80. Seawhite also supplies Cass Arts in London so it’s possible that it can also be found at those stores.

As I’ve said, the surface is typical for recycled card .. very matt, even slightly dusty in look, and grainy, with the odd larger speck here and there. The overall colour, a light coffee-brown, is very uniform (not mottled or patchy) and consistent from one sheet to another. There is no visible distinction between ‘front’ and ‘back’ of a sheet. Against the light the surface shows a slight roughness, like ‘sugar paper’, but surprisingly the internal corrugations aren’t visible even under glancing light. The surface picks up grease from the fingers quickly and visibly, because it’s unsealed and very absorbent. It may be a matter of opinion as to whether this matters, but if you want to keep the material as clean-looking as possible while working you’ll need to wear cotton gloves.

No exact thickness is provided by the supplier, but 10 pieces tightly pressed together come to 18.5mm thick, so for structural and scale purposes one can take the thickness to be c.1.85mm. Being hollow it is easy to cut through cleanly, though as one would expect cutting is much easier and smoother along the direction of the corrugations. Contrary to what one would expect though, the card seems to stay just as rigid in both directions so one doesn’t necessarily have to choose to cut in a particular direction for stability. It’s also very firmly bonded internally, so for example even very thin strips stay straight and intact. In fact, for something that’s basically just a hollow construction of heavy paper, ‘Kraft board’ maintains both its rigidity and coherence incredibly well!

kraft board

How to work with it

Because the surface is speckled it can be easy to lose pencil marks made for cutting, so I would recommend circling them lightly, as shown below. After cutting, these can be removed with a soft eraser.

marking out for cutting

Despite appearing soft and easy to cut with a scalpel, ‘Kraft board’ is deceptive. The paper itself is very tough and needs a sharp point to cut it cleanly. The hard fibres in it will also blunt the tip of the blade very quickly. It would be senseless, and expensive, to replace the blade that often .. but sharpening just the tip on a piece of 800-1,000 grit wet/dry paper as shown will help.

sharpening a scalpel

I always recommend patient cutting, i.e. starting with gentle passes and not trying to cut through in one go, but this is particularly important with ‘Kraft board’ otherwise the edge will compress or parts of the paper might tear. For more advice on marking out and cutting generally, see ‘Main construction’ in Methods /- Making realistic models.

The following sequence of photos shows the steps, techniques and additional tools recommended for making a simple ‘box’ form, i.e. a building block comprising roof and walls. Although this is the simplest possible exercise, it illustrates many of the basics of effective construction with this material. The first advice is that, since the model is mostly viewed from above, roofs assume more significance so the overall look will be cleaner if these are complete and without seams (i.e. walls stuck underneath them rather than around). I’ve found that generally the cleaner way to build this type of model is the opposite of real construction .. building from the top downwards.

simple blocks

I’d also recommend that the walls should be cut with the corrugation running from top to bottom, so that the corner seams are less obtrusive. The distinctive ‘zigzag’ patterned edge that occurs when cutting in the other direction cannot be completely avoided in the model .. and can sometimes be used to good effect! .. but it can at least be controlled with a little thought.

In the photo below, the top piece has been cut together with a much longer piece for the sides, long enough for all four. This ensures that all four walls will be exactly the same height and that the box will stand well when reversed. The next ‘trick’ is to measure from the cut roof and divide up the strip only as-and-when each piece is needed, rather than measuring/cutting all pieces out beforehand. This avoids many of the slight discrepancies that are bound to occur.

longer strip for sides

I use solid metal blocks as supports for gluing. These ensure that the wall, shown below, can be positioned correctly on the edge and maintains a right-angle. Steel blocks like these are not available in D.I.Y stores but can be bought online at, for example, The best glue to use when working with any card is Pva wood-glue because it’s strong, clean and allows for some repositioning. But better still are good quality wood-glues from Evo-Stik or Loctite rather than the weaker ‘school’ Pva. These make the work easier because they grab and set more quickly.


measuring insert

Above, I’ve glued the two parallel walls first and waited a little for them to become firmer. Then I’m marking the length of wall which needs to be cut and inserted between them. Usually this results in the best fit. Below, the glue needs to be applied to this piece rather than the insert so that the glue isn’t squeezed out onto the surface when it’s pushed into place. Pva glue need only be used very sparingly with this type of card.

applying wood glue

Below, once the piece is inserted the work can be turned around and a flat surface used to level the wall into position. A good Pva glue will hold absorbent cardboard firmly enough for handling after a few minutes though it will take longer for the glue to fully harden.

using work surface

Essential and recommended tools

I’ve written more about these tools in other articles such as ‘Main construction’ which can be found in the Methods /- Making realistic models section, but I’ll repeat the main points here.

Scale ruler There are two types in common use for metric measurements .. flat, 2-sided and triangular, 3-sided. The flat ones may look more elegant and sophisticated, but my preference is for the triangular because they are often clearer, with bolder calibration. They are also a little harder to lose amongst the clutter of a work table. The one shown in the foreground below is actually more for interior or theatre design, the smallest scale included being 1:125. Architects’ scale rulers have a greater range, usually down to 1:2500. Because of this the scales are paired on each of the six edges i.e. 1:1250 with 1:2500 etc. If you want to read more on working with scale rulers see the article ‘Working in scale’ in the Methods section.

scale rulers

Mechanical pencil It is essential to use one of these, shown in the photos above, to make a consistent, fine line when marking up for cutting etc. But this doesn’t need to be an expensive one .. the cut-price ones from any supermarket will do almost as well. I personally prefer to use a special type though which takes a 0.3mm ‘H’ lead, finer and harder than the usual ones, which gives better accuracy.

Scalpel or fine cutting knife I prefer a surgical scalpel, far left below, because it cuts better, is easier to control, and the blades can be more easily re-sharpened. These are made by Swann-Morton, the best handle size is No.3 and the best general-purpose blades to use are ’10A’. The more common type of fine cutting knife to the far right has a round barrel which is more difficult to keep steady and the blade wobbles more because it is less supported. There is one drawback in choosing the scalpel type, and this has started happening only in recent years. For some reason, perhaps because of cheaper manufacture, blades are almost impossible to slide onto new scalpel handles without the help of pliers. One should be able to do this comfortably by hand, but the fit is just too tight.

fine cutting knives

Small try square The one in machined steel shown below is more properly termed an ‘engineer’s try square’ but other, usually 25-30cm ones can be found for general D.I.Y or woodwork. It’s possible to survive without one, but being able to check and mark out right-angles, especially repeated ones, like this can safe a vast amount of time.

try square

Cutting mat The size depends on the size of models you are likely to make but usually an A2 cutting mat is more than enough. It’s best to opt for the cheapest deal you can find if you need to save money because the ‘quality’ doesn’t really make any difference. What matters more is that it’s kept clean .. put aside while painting or especially supergluing because these will quickly make the surface less effective. Whichever brand or source, I would recommend one with a prominent centimetre grid as shown below, because this can help a lot when cutting parallels.

masking tape on metal ruler

Flat metal ruler A metal straight-edge is essential for cutting against and in my experience the best for this purpose are the cheaper, flat steel ones. These are normally available in four lengths .. 15cm, 30cm, 60cm and 1 metre. As with the cutting mat it may be difficult to determine which size will be needed most, but I would recommend that if you opt for a 60cm you really have to get an additional 15cm because it’s a pain having to manoeuvre the long ruler around for small cutting. A strip of masking tape on the back of the ruler, shown above, is essential to make it grip better.

The advantages of making ‘slotted’ forms

The special rigidity of ‘Kraft board’ makes it an ideal material for trying slotted, interlocking forms. This was how I put together the structure shown in the first photo and below, also in close-up.

slotted construction

slotted form close-up

It is just a series of identical floor shapes and identical upright supports with slots cut so that they can interlock, and dependent on the stability this might not even need to be glued. It is by far the easiest way of achieving multiple storeys and uprights which are all reasonably aligned and straight! To achieve identical cut-outs I made Pvc templates first, around which each form is traced in pencil on the cardboard. I had to make the slots on the template a little wider to compensate for the extra width of the pencil line.

slotted storeys with template

This might be a little clearer from the following photos showing a similar, earlier construction.

components for hexagonal building

hexagonal building

It is common practice to indicate slopes or variations of the terrain in layers corresponding to the height levels on a contour map, as shown in some of the photos above. Once again this is easier from the top downwards, cutting out the smallest shapes first and using these as templates for the larger. I prefer to fix these together using evenly spaced pieces of strong double-sided tape, but Pva glue can also be used. This should be applied in small, fairly widely spaced spots (spreading too much glue will cause the cardboard to warp) and ideally the layers should be weighted down while gluing. UHU can also be used for this in a similar way but this needs to be done quickly before any of the glue spots dry out too much.

While working on these landscape layers I looked at another interesting way of creating a smooth gradient by constructing the building blocks first, cutting holes in the card and positioning this around them at an angle, as shown in the photos below. With a relatively simple model this would be a lot easier than sloping the bases of the buildings.

buildings inserted

angled for slope

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