Useful hobbies are all around. Mine is to build paper models. When I was a child I built quite a few plastic kit models. Cars, aircraft and military vehicles mostly. I thought I had some experience building scale models.
Then I tried building one using paper. There are no pre-made parts or shapes. When working with paper you have to form the parts before trying to install them to the correct place. Every part is a little model building task in itself. You'll probably have to print a part several times until you can bend and shape it correctly. If you are a beginner on this field, you'll need more time to get the shape you need. The only rule I found is to not give up.
It feels nothing short of terrific to start with a simple sheet of paper and build something spectacular. A little wonder, crafted of patience and manual dexterity on the forge of perseverance. As you spend time building these models, you'll find yourself to be a better and more experienced model builder.
Your initial efforts will turn into results and by the time you will have filled your shelves with "paper-horsepowers", you'll be rightfully proud of the creative pastime you'll have picked up along the way.
OK, let's get a bit closer. What's the first step to start building your model with? I suggest trying yourself first. Maybe it isn't for you. Don't buy many expensive tools, accessories, glue, maybe a new printer if you don't have those already. Choose a cheaper art knife with some spare blades and use some old newspaper to save the surface of you desk. These will do at the beginning. Any transparent glue recommended for paper is perfect for first-timers. Pick the non-toxic ones if possible. You can find many free models in all topics. Use your favorite search engine and type the followings:
"papercraft" + "your topic"
Change "your topic" phrase to what you like. It's simple as that.
Another option is to get printable patterns from this site
Having downloaded the pattern, print it on the proper paper. The common typing-paper is not the right choice, because it's too thin and weak. It hasn't got the structural strength needed. The surface of the paper depends on your needs. If you are planning to assemble a car, for instance, I suggest to choose glossy paper. In case the real life model has matte surface, you'll want to use matte paper to print on. By the way you'll find it useful to combine the different paper types. I apply this technique often for complex models.
So, you've printed you first model. What to do? First, find a good box or tray for the cutaway parts! I think you don't want to waste your time searching for lost parts. If you don't have a container for the little parts you will lose them. It's a law of nature like the sky is blue, grass is green and little parts keep escaping...
Now, we have all the things we need to start. Grab your art knife and start to cut out the parts along the indicated lines. I have a technique to keep an organized layout. I never chop the paper into little confetti. I usually cut along the cut-lines only, that way you can find the part's inverse copy on the paper. This will helps you identify the parts later.
About the rulers... I think rulers are non-effective tools at this time. 99 times out of a hundred of I don't use a ruler. Rulers will slow you down and are generally unnecessary to cut the lines. I use it only if the line is very long... really.
Before you glue the parts together or bend them, it's recommended to paint the white edges. Much simpler to do this now than after the assembly. I used to paint the edges with felt tipped pen. This is the most efficient way I've found, because I can color the edges quickly and without many mistakes at all. Felt tipped pens are easy to buy, and not a costly investment.
You can start to bend the pieces now. There are two kinds of inflection exist: hard and soft. The type of the inflection will affect the final look of your model, so it's recommended to choose the right for every situation. You don't want to see hard edges on a nice smooth hood of a car even though it isn't flat... Check the environment of the mentioned parts and think a little.
Try to roll the paper slightly if you only need a curve. Maybe you need to do it several times till you get the right shape. Do it until the parts fit perfectly. Remember it's not a race, the results count not the speed of assembly.
I use a toothpick or often a little piece of a paper to glue the flaps. Every flap must be in the right position before fixing the parts to their place. Don't use too much glue, because it can make the paper wavy. You don't want to see that... The other extremity is using less glue than enough. The piece may seem to have been fixed properly, but when you try to connect it to another, the joint will burst. It cause other headache. So, always try to find the balance.
In the case of industrial style models, like cars it's recommended to proceed symmetrically. If you assemble the left side before following with the right, you will have discrepancies between them. In other words you won't make the same mistakes. It causes your car to be asymmetric. The human eye picks these differences up easily. So, if you'd bent the left door more than enough, do it with the right too. You can compensate for it later, but at the end your model will look symmetric. Symmetry is not so important on organic models.
As you make more and more papercrafts you'll become more experienced. You'll find solutions and way of doing things that fit you. Maybe, in time, you'll design your own scale-models. Every time you look at the model you had built, you'll realize how nice it looks. Nice and precious for you because it contains all those work hours. The truth is, it contains a little piece of you.
Tibor Nagy is the author of Paper Cars e-book which contains some printable templates for high detailed oldtimer cars. Visit his site on: http://www.papermotor.com