... but enough about me!

Let's cut to the chase. You're here because you want to make your own robot costume! First you're going to need a bunch of stuff. Also your place might become a dump during this process. If you have one, prepared to not have a significant other after you're done. Unless you're a sweet talker, then you can smooth it out no problem.

I'm going to try to make this as helpful a big-picture as I can. There are tons of individual videos and tutorials for very specific aspects of cosplay creation. What I notice less of is a sort of guide to help prepare you for what to expect because once you start, there are lots of points in the process that can bring you down and make you want to quit. Read this. Read this and don't quit. Look at that disaster my house turned into. Something beautiful emerged from that. And it was worth it.

Supplies

EVA Foam - sheets or interlocking pads. You can find these in most stores and JoAnn now sells sheets of them (sheets are better to work with than pads, in my opinion). You can also find tons of options online so don't be lazy and hit up that Google search.
Contact cement - most people online use Barge(quart) but that's all hive-mind talk. I use Weldwood (gallon) which you can probably find at home improvement stores like Lowe's. It's less viscous so it's a little easier to work with and it sticks just as well as Barge does. They also come in pints if you don't think you'll be needing a whole gallon. Both options are more cost effective than Barge and work exactly as well.
Razor - preferably with interchangeable blades, like this inexpensive Graphics Knife. You need sharpness to do this well.
Replacement Blades - like these are great. Not too pricey for 50 blades, but this will add up over time since they can dull pretty quickly, so just get one of these and the sharpener below
Sharpener - Your blades are going to dull and make your life miserable so have a good sharpener or be prepared to switch out those blades a lot! The one I linked to is great and super cheap.
Poster Board - big thick paper, ideal for getting started!

Silicone brush and/or Spatula - Some people prefer brushes, but the only kind worth using are these silicone brushes because when the contact cement dries, you can peel it right off like a booger. However I find using this set of spatulas ideal because you can spread glue neatly and easily and cleanup is even easier than with a silicone brush!

Optional, but recommended

Power tools - Band saw, scroll saw, rotary tool, belt sander, hand held belt sander, laser cutter/ engraver... etc! Power tools are great to have but absolutely NOT necessary. You can create amazing costumes with the simple list above. If you already have these tools then definitely use them but remember... they're just tools and not a replacement for skills, experience, and practice
Wax Paper - like silicone, wax paper is not a surface that contact cement sticks to, so this will help you control your glue-ups

Step 1: Find an Idea, or Lots of Reference If You Already Have an Idea

ok, I'm going to skip step 1 because it's pretty obvious. First you need to have an idea of what you want to make, which you probably already do. Some kind of robot, maybe?

(btw, just so you know I will be using pictures from a couple of different builds to help fill out this instructable, because I haven't properly documented any single build from start to finish. I get caught up buildy building, and forget to do the piccy pic-ing.)

Step 2: Big Shapes

Look at the design you're trying to build and train your eye to ignore the little details. This takes practice, but it's critical for building stuff like this because you can't build a house without first making the foundation.

This skill will keep you from getting overwhelmed. Looking at a really detailed surface makes me feel like it's going to be impossible to replicate. Instead try to imagine it as layers of detail, starting with large simple shapes and getting progressively smaller. This makes it more manageable for your brain to understand the road ahead.

Look at the armored princess image... there's a lot of detail in that armor, but if you look at the paper cutouts in that image you can see how I found the main basic shape of each part. Those are my big shapes, my base forms. Once there, you can then start building details on top of that.

Step 3: Paper Tests

The best and least expensive way to start building your shapes is to rough them out on paper. I use poster board because it's sturdier than regular paper but still thin and easy to cut, bend, and shape. It's also way cheaper than foam and faster to work with.

Look at the big forms I mentioned earlier and try to figure out what parts of it would look like flattened out. Anywhere there is a hard edge can be a separate shape. For example, a cube is made of six flat squares, all flat shapes taped together into a 3d form.

Roughly draw your shapes and quickly cut them out. It's important, at least to me, to draw rough and dirty, don't worry about straight lines. Quickly and cut them out without trying to be precise in any way. This is basically the "sketch" phase of the project in which you're experimenting and trying out ideas. Prototyping should be done fast so you can iterate several times to nail down the desired result. Remember that nobody does anything perfect the first time.

Tape them together and see how it looks. Shape not quite right? Cut them where they need to be shorter, or tape additional paper where it needs to be bigger. You can also put that shape down on paper and trace a new shape with the modifications you think it needs.

Keeping working it until you're happy with the result. If you like you can cut it all apart and trace a neater and straighter version for a clean template to work with. At this point you can use a ruler for straight lines and any tool you like to help you get nice curves. This is where the refinement happens before moving on to foam.

Step 4: Transfer Paper to Foam

This step is pretty straightforward... in order to cut your shapes out of foam, you need to trace your templates onto the foam. I like to use those long thin needles with the colored balls at the end to pin the templates down onto the foam so they don't move while tracing. You can use black marker on white foam, white marker on grey or black foam... in the end I discovered I like to use mechanical pencil on all foam. It can actually score the foam instead of just putting a line on it which is visible on all colors, and it's also super precise compared to fat-tipped sharpies (ironically not that sharp).

The best way to go about this stage is to lay them all out on your foam and start arranging and rotating them to try to squeeze them all into the tightest area you can. If you're made of money then you don't have to worry about this but I like to keep costs down and use my foam as optimally as possible. Think of it as a puzzle game to master. Just remember to leave a little space between all the parts so you can cut them out without damaging neighboring parts.

Also, be aware if there's anywhere you need an OUTER BEVEL in your cut. I'll talk about bevels soon..

Step 5: Get the Angles!

For hard surface builds (anything with hard angles like robot parts), I find it really helpful to measure the angles between surfaces while it is still a paper mock-up. This handy tool you can find at a hardware store is helping me figure out the angle from one surface to another. Once I have that angle I divide by two, and THAT number is written down on each surface because that is the bevel that I will need to apply to the cut in order for the two pieces to match up properly. Does that make sense? Hopefully it does That last picture shows the bevel used to cut a shape with that 'angle-divided-by-two' result.

Step 6: Bevels!

In order to create interesting shapes, you're going to need to make interesting cuts! Beveling your cuts just means you're cutting the line at an angle instead of perpendicular to the surface.

In the first picture above you see one of my shapes cut out with a bevel applied to one of the edges. In the next 2 photos you see how that bevel helps to shape come together. If I had instead cut the shape without this bevel it would have just lined up to make a flat sheet instead of a 3D shape. Remember that cube I mentioned early on? When using anything with real thickness, unlike with paper, you need bevels for them to come together properly. So each of those squares would need this sort of cut in order for the cube to come together properly.

Step 7: Cutting

I can't really show you how to cut properly using pictures, so here's a link to a video from Punished Props showing some really good techniques. This link starts at the cutting techniques, but if you watch the whole thing you'll get some decent info on blades too.

Of course, if you have access to power tools, I find a scroll saw (with a spiral blade) and a bandsaw (with a scallop blade) are the best ways I've found to make cuts.

The bandsaw is great for making long straight or curved cuts with or without a bevel. Since the table rotates, you can dial in the exact angle you need to bevel before you start and know it'll stay consistent.

The scrollsaw is great for tighter curves, and if you use a spiral blade like I do you can cut in any direction without having to rotate your foam.

There are so many different techniques and tools you can use to cut foam. Experimentation is the key! For example, you can use metal pipes or diamond covered hole-saws to cut perfect holes and circles.

Step 8: Rough Tests

Ok, the paper forms you created turned out great and you're pretty sure they're going to work out... except for that one part, or that tricky curve you couldn't quite do with paper. Paper can bend one way or another but it cannot do compound curves so you might need to do a foam test.

In this case you'll want to use the cheapest foam you can find to test your shapes. Check Harbor freight or Walmart.com. Trace your template onto the foam and cut it out. Heat the foam and shape it if necessary and glue it together. Much like the paper stage, don't try to make this test perfect.

The first image above shows a test I did of a chest piece. I knew I had the shapes right, but I wanted to know if I could pull it off as one big puzzle piece to reduce seams between shapes. I decided I didn't like the round look to it and much preferred the crisp edges i got when making each shape a wholly separate cutout.

The next three images show some more shape testing.

The wheel was interesting because I was going to use the wheels off an abandoned Power Wheels toy, but they turned out too heavy. I knew how I wanted to go about making my own foam tires but I wasn't sure about bevel cuts and size parts so I went straight to a foam test. I came close, but wasn't quite there. I did nail it with the second try (I had a good feeling about it so I went with the good foam for the second attempt).

Again, I tested out my idea for the tread pattern with scrap foam before deciding how I was going to do it.

Step 9: Support Structure

You need a way to keep everything together. You can't just make a bunch of parts and throw them at someone and expect them to stick where they're supposed to.

A support structure is anything you need to build under your costume to keep it all together. In the pictures I show a PVC frame that I built to support the wheels on this costume. PVC structures are relatively cheap and easy to build so it's a good choice for anything big.

The last picture shows one of the forearm parts, but if you look inside you can see furniture foam glued to the inside of the bracer. I love using furniture foam as a support structure inside parts that go on your arms and legs because:

It's very squishy, This means you can get in and out easy and it'll form itself to your body without any painful contact points. It also means it'll work for a variety to body types, so a sknny person and a muscley person can wear it just as easily.
It's very... frictiony? It's great at keeping the part exactly where you put it
It's cheap and easy to use, just cut out wedges and glue it in there

One support structure I've used was a backpack (this Bastion build is actually attached with a small child's backpack I got from goodwill for a dollar. Everything clips on to that backpack). Another support structure I've done is simply sewing velcro patches onto tights. The thigh armor of Bastion stays in place with nothing but a square of velcro on the hip and one in the inner thigh.

Step 10: Glue Parts Together

Contact cement is a very special kind of glue unlike most others. You don't really slather it on and slap two pieces together. That's a recipe for guaranteed failure with this stuff.

To properly glue your parts together you need to apply a thin layer of glue to each part where they will connect. Wait 5 minutes until the glue no longer looks shiny and wet. It should be tacky to the touch, but not pull and stretch to your finger.

Apply a second thin coat of glue over both parts and wait for it to dry again. Once dry and tacky it is ready for you to carefully and slowly press both parts together. For complex shapes you may want to use wax paper to keep glued areas away from each other until you are ready to stick them together.

Step 11: Constantly Check Scale, Fit, and Shapes

If you don't constantly check how it's all coming together you will be hit by some nasty surprises! Even doing so I was still having to make a couple of major changes to a few parts! My son wasn't around when I was working on the back of the boots, so I went ahead and guess how they should be done but it turned out way too big and became impossible to wear so I had to cut them off and heavily modify them... That's another one for the mistake column, but I recovered :)

Step 12: Don't Forget About the Big Picture

It's important while you're working to keep your mind on the overall big picture. It's easy to start getting lost in working on small details on one part while you still have huge important parts incomplete, or worse, not even started.

In the last picture with the white foam you can see that I built and detailed everything here... buuuuut I don't even have thigh armor, groin armor, and that belly was a leftover from another build that won't work here. I got lost in details and started running real low on time so the end result of these missing parts turned out to be much lower quality than the rest of the build. In fact I never got around to the belly or groin. The thigh was the only thing I got done, and pretty poorly at that. Live and learn though!

Step 13: Mistakes

Mistakes. They happen. They're part of the process and ARE surmountable. Sometimes you screw up, other times things don't work out how they should have. Maybe a shape doesn't form the way you expected it to. Just remember that everything turns out better the second or third time. Each attempt increases your experience level, and you level up FAST in this game if you keep at it. Nerd.

The foam shape in this picture was a failure. The paper shape was my second attempt at that shoulder pauldron

Maybe take that messed up part and re-use it somewhere else. Get creative, just don't get down about it.

Step 14: Details, Paint

The devil is in the details!

Thin sheets of foam is great for cutting out details to glue onto the surface like metal plates and grills.
Hot glue as I mentioned before can be used to simulate weld lines.
Mix cotton batting with liquid latex and apply onto the foam for a very rough texture.
Wood burners are great for engraving details and lines and 'rivet holes' into your foam
Another good option for those lines is to slice the foam with a razor and then use the heat gun on those slices, this will open up the slice and leave you with perfect panel lines.

There are so many options for painting. For the most part people tend to use a "sealer" like black plasti-dip spray to coat the foam and seal it to prevent it from absorbing whatever paint you decide to go with. This works like a primer before you paint your walls.

You can spray paint, you can airbrush, you can paint brush. Clear coat, metallic, texturized... There are so many options and it all depends on the build you're making.

To keep things simple for your first build I would recommend a thin coat or two of plasti-dip and then buy some acrylic paint from your local hobby store. Brush it on in thin layers to reduce the amount of brush strokes you leave behind. Start with solid base colors, after that you can add trim and detail colors. Follow it all up with a clear coat to protect your paint job. Then add some weathering.

The best way to do this is to use a small amount of paint in the browns, blacks, and deep reds/oranges and water it down a lot. Brush this quickly all over and wipe it all off with a rag. I prefer cloth rags because paper towels leave behind so much dust and fragments. When you're wiping off you can't easily wipe into all the corners and that's a good thing! Dust and dirt naturally collects into corners on objects in real life, so that's where you want most of this watered down paint.

Step 15: Lighting/Electronics

Lighting adds such a cool element to almost any costume! It's not really hard to do if you want to do something quick and easy. They sell all kinds of very small LED units with batteries built in you can just attach wherever you need it.

Taking it up a notch if you want to do something more custom, you can buy an inexpensive LED kit that you can use to put lights anywhere you need them. A quick search online will help you get started on wiring them together, which also isn't that hard. Check out this book if you need something to get you going. You can even get them lighting up in flashing patterns or flowing and pulsating displays.

You can even buy LED strips, string, pucks, wands, and all kinds of crazy and useful items you can put to use.