How to Make a Transformers Cosplay: part 1
(This tutorial is meant for people with little to no previous costume-making experience.)
The purpose of this little article is to get the newbies started and not point them in a direction, per se, but rather show them all the directions that they could go, and which might suit them best. I'll have other tutorials up relating to my favored method of construction.
Alrighty. So you came here to learn how to make a TF costume, but you might not know where to start, right? That's totally fine, because that's what this is here for.
Making one of these rigs (which are solid suits) or softies (which are soft/pliable suits) takes time, money, and commitment. I actually think Alley Cat Scratch (one of the definitive LotR costuming resources) sums it up quite nicely:
I want it now!
I want it cheep!
I want it to be perfect!
You only get 2 out of 3!!!!!! Pick carefully.
Since you're relatively new to the whole costuming thing, much of your time (and possibly money) will probably be spent getting used to the materials. And that's fine: trial and error is all part of the process of learning.
Another thing to take into consideration before you dive in is your future workspace. Survey the space that will be available to you, and take that into consideration when choosing working methods as well. Some materials require more space to use than others, and some require you to work outside as well. (So if you plan to work in your apartment, then fiberglassing is probably out of the equation.)
Got all that? Okay, let's move on...
Picking a Character and Design
Odds are, you probably have a character in mind. Some people do, which is cool, and some people don't. If you do, then my advice is to stick with the most basic of that character's incarnations. Usually, that means G1 Sunbow (cartoon animation model) or an TF:Animated design. The two of those require completely different working methods and are easy for different reasons, but I'll cover that later.
If you don't have a character in mind, then I'd suggest that you start off with something simple and boxy. Boxy shapes are very easy to make, fit, and finish, and you can make them cheaply. Popular starter characters are Soundwave and Optimus Prime, because their designs are so simple.
Picking materials and working methods that suit you best are key to having fun building a costume... and finishing it. This might sound obvious, but it's important in several ways that you might not even have thought of!
Here's a link to the TransCostumers materials wiki.
From here, you can get a jist of the kinds of materials people usually work with, how they use them, and how difficult it may be to use them. Use your best judgment on which would be good for you.
If you don't have any prior experience working with anything on the wiki, cardboard is typically the material of choice because the learning curve is small, and it's great for a beginner's boxy costume. Costumes made from cardboard would be considered rigs because they're structurally solid, and are appropriate for G1 design types.
However, if you wanted to go for a TF:Animated costume, cardboard is probably a bad choice. Why? Because Animated designs are comprised entirely of complex curves (meaning, shapes that curve in more than one direction at once, like a dome versus a cylinder). So for those kinds of designs, foam and fabric (or things that bend easily) will probably be better for you. Though really, it's all up to you. If you're really good at making complicated shapes out of flat surfaces, then there are lots of other possibilities.
Two things to keep in mind, though, are space constraints, and your own personal work habits. Space dictates how and what we're able to work with a lot, like I mentioned above. And the other thing... personal work habits. Only you can really know if you're going to like a certain method or not. If you like mathematical precision and geometric problem solving, then you might like using cardboard, or pepakura. If you like sculpting and carving, then maybe casting, wonderflex, or upholstery foam might be your thing. If you're really good with paint, then by all means, paint!
The point is, don't go with a method that requires you to do stuff that you hate or are bad at, because you won't want to work on your costume. It's as simple as that.
Questions to Ask Yourself
1. How much money do I have to spend? Do I have it all now, or only part of it to start with?
2. How much room do I have to work?
3. How much time do I have to work?
4. Would I rather "sew" or "build"?
5. What character do I want to make?
6. What is my skill level in relation to the detail in the character design?