Following are my answers to some of the FAQ addressed to Digital Navy. Some of them are very general questions, some are more detailed, but all apply to our models. What you will find here are my suggestions as to how I would approach particular problems, but I don’t claim that these are the only methods and solutions. These simply work for me. 

1.What paper to use?

2. What does it mean to “double” the part to 1mm of thickness?

3. Why are there no “tabs” on many parts?

4. Photo-etching in paper - how to do it?

5.How do you make those paper gun barrels?

1.What paper to use?

This is one of the most important issues for “digital” card modelers. When you buy a printed kit you don’t have a choice - you just have to live with whatever the publisher gave you. On the other hand, you can  print digital models by yourself, and this gives you a great advantage but also presents you with a hard decision - which paper to use.
There are detailed descriptions and comparison charts for different kinds of paper on the net -  check out Saul Jacobs’ site or Steve Brown’s FAQs - here, I will describe some papers I use myself.

In the past, I’ve relied heavily on  #1 and #3 plate bristols. These were thick, 100lb, 2-ply bristols with good forming characteristics. By good forming characteristics, I mean - for example - that they didn’t break when rolled and the layers of the paper did not tend to separate. The drawbacks were that, as art papers, they come in 9”x12” size and have to be cut to 8.5”x11” sheets before printing. They also displayed some bleeding when printed on my Stylus 980, especially when printing thin black lines. Bristol #2 had similar qualities but was thinner - I used it for some delicate small elements like ship planes. Nowadays, I most often use Hammermill card stock - #4. It’s a bit thinner than bristols #1 and #3 ( somewhat between #3 and #2 ) - 74lb weight. I did not notice any bleeding so far with this paper. It does, however, have some tendency to break when rolled in tight cylinders, and you have to be careful when handling small parts as the top layer of this paper can separate and fall off. The paper is cheap ($10 for 250 sheets) and is 8.5”x11” in size - big pluses. Paper #5 is probably the cheapest paper you can find in Staples and the most generic copy stock. But it is one of my biggest discoveries in card modeling - the discovery that I can print some elements on this thin paper (20lb) and roll perfectly shaped tight cylinders - gun barrels for example.    

2. What does it mean to “double” the part to 1mm of thickness?

The word “double” may be misleading - “laminate” is possibly more precise. What I mean by this is that some parts, pointed out on the sheets or diagrams, have to be “laminated” or reinforced, so the thickness of the part treated this way is 1mm. Normally, the paper you will print on is 0.1 - 0.3mm thick, so it’s obvious that just gluing together two pieces of this paper won’t do. You can either use three or four layers of the basic paper or just one of appropriately thick cardboard. I prefer the latter solution as it requires only one glue application.

There are two reasons why some parts need reinforcement. First, some parts need to be less flexible, for example all elements of the ship hull. Second, sometimes more gluing surface is needed. This is illustrated in Fig.1. Case #2 is a regular “tab” connection. As I don’t like this type of construction, I prefer the connection depicted in case #1, where no “tab” is involved. The joint is cleaner and more precise but it requires that the gluing surface be incresed by “doubling” or “laminating” the part. This issue is connected to the next FAQ:

3. Why are there no “tabs” on many parts?

Because they are not needed in most cases. As I mentioned above (see Fig.1), using tabs usually results in unsightly gaps between connected parts. Fig.2 shows, in an exaggerated manner, a gap which results when gluing a part to a flat surface - see case 1. Case 2 illustrates how to avoid the above mentioned gap by using a separated tab, a tab that is not created by bending a section of the part but is a separate piece of paper. Since tabs are not visible on the finished model, they can be made from scrap paper if the kit you are building doesn’t supply them on the sheets.
Related to the “tab” issue is the  way in which parts are designed. Fig.3 and 4 show three different approaches to designing a simple box. Cases 1 and 2 on both pictures illustrate design which relies on “tabs”. Case 3 demonstrates a design principle widely used in Digital Navy models. 

4. Photo-etching in paper - how to do it?

Onboard catapults, chart house windows, platform supports etc., all these elements require precise cuting and bending of delicate patterns. Plastic modelers simply reach for a fret of photo-etched parts to offset plastic kits’ inability to replicate the above-mentioned patterns with satisfactory quality. Also, they usually have a lot of problems with proper shaping of the photo-etched parts, painting them etc.
With paper, we don’t have to go this way. Lets photo-etch in paper! The secret lies in the proper sequence of operations.
I’ll illustrate all of them on the following pictures.

1 - cut out the portion of the sheet containing the part which is about to be “photo-etched”. Then, before you start cutting out all those small “empty” areas, score all of the bend lines and make all required bends. Esentially, form the part to its final shape before any cutting work is done. At this point, I often paint the reverse side of the paper in matching color.

2 - cut out all inside “empty” spaces, leaving intact the paper around the part. This will make holding the part in place easier.

3 - When all the inside cuts are done, “free” the part from the rest of the sheet.

And here you have it ready. Since all the bends were already formed, you don’t have to endure all the pains plastic modelers go through when bending and forming real photo-etched parts.

5. How do you make those paper gun barrels?

This is how I do it - first of all, I print gun barrels on very thin paper - like copy paper #5 on the picture above. Cut out the part and run it a few times on the edge of the scissors. This will give it some tendency to roll. Note that, in the case of the gun barrels, the parts are sections of the cone, not cylinders. Nothing looks less convincing than cylindrical gun barrel - smoke stacks are cylindrical, gun barrels are conical! Next, start to roll the part as tight as you can - for now without applying any glue. You may help yourself with a small bit as a rolling guide. In the case of really thin gun barrels, just roll the paper on itself - don’t worry that initial bends are not smooth, they will be covered by subsequent layers of the paper. (See Fig.10) 

When you have the paper “worked down” enough that it rolls easily, it’s time to apply glue. For this, I exclusively use Barge rubber glue. Here, the adhesive needs to be very tacky but has to give you some time to adjust, if necessary, the orientation of the surfaces being glued. Roll the part almost to the final shape, leaving only a narrow, 2-3 mm section unrolled. Not letting the part to “spring” back and unroll, apply a thin coat of glue and complete the “roll” so the printed areas of the paper line up. Next, roll the part between your fingers for a moment. Because the glue is not completely dry yet, small imperfections in the position of the edges of the paper can be corrected. This way, I was able to make, for example, the main gun barrels for the H.M.S. Dreadnought in 1:700 scale, or 5” aa guns of the IJN Fuso in 1:250 scale, all of them with nice tapper and proper scale thickness.