Noob Questions on Foam Building.

sorry if this is in the wrong place, but i'm new here and i couldn't find a "help" forum or anything similar. i've also posted this on the rpf, but not getting many responses. anyway, i've just started trying my hand at making armors out of foam and i'm not satisfied with how it's turning out.

my main problem seems to be how angled i should be making cuts. when two faces need to be joined at an angle (see picture below), i obviously want them to line up and be flush with each other so that the outside is smooth and nothing is sticking out. i had to redo that specific join 3 or 4 times before i got it decent enough for me to accept it. often times i cut it and the angle is waaaay to acute or obtuse and then i'd have to scrap it.


the other thing is, when i form the angles, it looks good to me, but later on i realize that it's just a tad bit off and it throws off the whole piece. so if i'm doing my helmet and all these angles look good to me, by the time i've looped all the way around and now i'm supposed to connect to my starting point, i see that my angles have been a bit off and it doesn't line up correctly. if i try to force them to connect, then it warps the shape and it looks ugly. and my files (AZTLAN's armored batman files) don't tell me what angle these joins should be, and even if it did, there's no way i'd be able to replicate that in my cuts.

similar to that, i can't seem to reproduce the same shapes and angled cuts if it's supposed to be symmetrical. for example, if both the left and right sides need the same rectangular shape and i match up the two shapes i've cut out, they're a bit off from each other. maybe one is just smidge larger or maybe one extends vertically just a bit more, but they're almost never the same. ditto for angled cuts (angled cuts are a recurring problem for me). when i compare the two pieces, one is always a bit more acute than the other. so when i've completed the piece, all those little imperfections add up and one side looks a bit different than the other.

another thing that's giving me trouble is trying to read the pep files. so sometimes there are these thin strips of cuts i'm supposed to make (see picture below). i get that they're meant to help curve the foam, but i can't seem to execute it properly. for starters, that strip is pretty thin and i can't cut that cleanly. my blade will drag the foam just a teeny bit and it won't come out as a straight cut. the other thing i don't understand about this is how to join that together. am i just supposed to leave those as flat surfaces, glue them down, and then bend it all? or am i supposed to make angled cuts here so when i glue it together, it naturally curves.


the other part about reading pep files is i don't understand what to do when it says to fold. when you're doing paper pep, the dotted lines indicate where your'e supposed to fold your paper, but i can't fold foam. so how would i go about doing this with foam?


last thing is i don't understand how to paint it. and this is just me being dumb and literally knowing nothing about how to paint. i hear you're supposed to seal it and put something like 5 layers of wood glue. does that mean i apply a coat of wood glue, let it dry, and then do that again until i've done it 5 times? if i did that though, i'd probably end up with a bumpy surface, right? i mean some areas will be thicker than others because the glue can't be applied perfectly smooth. anyways, after that i'm supposed to add base coat and then a top coat. what's the difference between the base and top coats? are they supposed to be different colors? and if so, how do i decide which colors to use in order to achieve a certain effect.

i've tried searching for these things all over the place, but i can't seem to find the answers i want. maybe this is all intuitive and i'm just the one dumb idiot who doesn't understand any of it. anyway, i thank any and all of you who took the time to read and reply to me. and again, i'm sorry if this isn't the right place to post this stuff or if these are questions that get reposted often.

Rexosorous there are no bad questions. For someone just starting these are the most basic questions asked here. I'll try to answer as much as I can as clearly as I can.

Wanderer TJ's thread on Foam builds here. ande you could also check out HaloGoddess's tutorials here.

If you troll around the 405th long enough you will pick up tons of tips and tricks on foaming. Now, peping is primarily used for going the resin/fiberglass route but can be used for foaming. You will loose details but those can be replaced w/ craft foam pieces. The templates however are not 100% compatible w/ foam so some adjustments have to be made. You cant fold foam like card-stock. adn no matter how small you can cut, you will never be able to make some of those small pieces out of foam. Those usually get tossed out. If you look in the archives at most of the foam files.....there will be this large grouping of template pieces way off to the upper left side the page. those are the unusable pieces that you can't produce w/ foam.

Now about the seams.....getting the angle right the first time is only after practice and experience. Some never get that far but take heart, there are ways around those little mistakes. The most accepted cut is the 45 degree cut. You won't always need 45 but the most critical part is the cut itself. How straight it is. this will determine the smoothness of your armor. even then there could be some puckering and gaps . these can either be sanded down or filled w/ silicone/caulk. When joining 2 sections, you might want to try doing a 45 on one side only instead of beveling both sides.

Now I did say that you can't fold foam like card stock but you can bend it as if it were. By making under cuts you remove foam along the inside of the fold you want to make. Don't cut too deep or you will cut right out the front. Just deep enough that you can bend the foam to the angle you need.

Foam doesn't necessarily need to be sealed but you can put a coating or 2 of what is called plasta-dip, which is a rubber type spray or paint that you apply to cover up any slight imperfections. I've used wood glue on a peped helmet and worked great but I never used it on foam. Other people swear by it but I find it to be to ridged and I feel that it would crack w/ a foam base. but to each their own.

Lastly Paint.......there is no right or wrong. there is only DO. What ever color you chose go w/ it and do it to your own tastes. If you want to go for game accuracy....that is fine. If you want to make a hippy Spartan....tie-dye the whole thing.......you are your own limitations.

You say you're a dumb idiot....but you were smart enough to come to the right place for answers.

Let me start by saying that using Pepakura with fiberglass resin is a better way to make details. You can then put foam underneath the fiberglass to pad it.

To make the angles you need to decide what angle is being used. I would recommend making templates out of cardboard for each angle. Use a scrap piece of foam to experiment.

The parts not lining up is a typical problem with foam Pepakura. That is one of the advantages with using card stock and resin.

If you are using an X-acto STOP NOW buy a soldering iron with a blade attachment. This will make cutting foam so easy you will never go back to anything else. I think you can get a cheap one for about $15. Alternatively you can make a foam cutting wire. It uses electricity to heat the wire, and the heat cuts through the foam.

Whenever you are trying to bend the parts I find that heating it up with a hair dryer and bending it makes rounded shapes. You should glue the parts together with hot glue so that whenever you bend the parts the glue heats up and bends with the foam.

To fold the foam you can make two pieces or slice a thin valley into the foam.

To paint it I would not recommend wood glue, use bondo. It is lightweight, sands, and paints very easy. Once you apply a thin layer of bondo hit it with a coat of flat black paint. Then use multiple layers of different paint to get the effect you want.

Just a suggestion, but why don't you do the angle cuts AFTER you join the pieces? To me seems
logical, but I've never worked with foam, (at least for prop building). Good luck on your build.

Here are some of my experiences working with foam in cutting and gluing pieces together for chest plates. Your concerns sound like what mine were when I first started. Helmets seem to be a different beast all together in regards to curvature so I can't say much there. I hope some of this helps.

Trouble overshooting or undershooting some angles during gluing - try this:
- Put a bit of glue (not much, just barely enough for a weak flimsy joint) hidden between the two pieces where the seam will be.
- Bend the two pieces about the joint a few degrees as the glue dries so that it is a soft adhesion.
- The two pieces should be stuck gently together
- Bend the two pieces to the angle you want as best as possible, then commit by gluing behind the seam (or wherever the glue will be hidden).
Summary: You lightly join pieces together, and then find the angle you want and glue them.

Identical pieces being slightly off in dimensions from one another? Try this:
- Make sure you are not wearing out your stencils.
- Replace your blades if they are getting dull frequently.
- Cut symmetrical pieces together with the same blade. You want the same mileage on your blade when cutting 2 (or 3, etc.) identical pieces.
- Stop cutting when you are tired (easier said than done).

Lasrig said:

If you are using an X-acto STOP NOW buy a soldering iron with a blade attachment. This will make cutting foam so easy you will never go back to anything else.

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I've done this method, and it does work but you run into the same issue.. your blade will dull.

IMO, stick with X-acto blades. They are cheap .Get a knife sharpener and keep it nearby, it will extend the life of your blade tremendously. Get to know how the blade feels once its sharp, and once it starts to get dull. Once your blade gets dull you'll need to sharpen your blade every few cuts, or just switch the blade (I only use the coarse side, swipe your blade thru it a few times, you'll notice its almost like new again). A lot of foamers switch their blades out after every individual piece.. thats not an exaggeration. I'm a cheap skate, and like to use a sharpener, that way I can get many pieces out of one blade. The sharper the blade, the cleaner the cuts for foam.

Lasrig said:

You should glue the parts together with hot glue so that whenever you bend the parts the glue heats up and bends with the foam.

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I highly suggest liquid super glue. Those one time use tubes? Those are great. Instant adhesion so you're not holding your piece of foam for 5 minutes waiting on your hot glue to dry so you can move on. And its sandable, it makes for the cleanest edges. Use hotglue on the back of the seams to make your seams stronger.

Lasrig said:

To paint it I would not recommend wood glue, use bondo. It is lightweight, sands, and paints very easy. Once you apply a thin layer of bondo hit it with a coat of flat black paint. Then use multiple layers of different paint to get the effect you want.

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Wood glue works pretty well, depending on the piece. If its going to bend and flex at all, don't use wood glue (it will crack). Wall spackle is great for sealing messy seams.

Bit of a necro post, but who cares, if it helps out answer a question.

I've worked with both pep and foam, and have quite a few projects on theRPF under my old username, RocFoamArmory.

-Pep is more detailed, but it takes FOREVER. At least compared to foam it does. Foam is much faster and you can get a great amount of detail. Plus, it's way more comfortable and mobile. But do whatever you want to.

- I cut every piece of foam I need with angled cuts. The only time I use straight cuts is when I know its on the outside edge of a piece where I need a thick edge. You can find out by looking at the model in Pepakura Designer. PM me for a key.

- Don't worry about what angle you need. I always do about 45 degrees, but it varies. The problem is not the angle, but how you glue it together. Put a thin line of hot glue on the edges of the angle that will touch, and join the pieces. They will still bend enough and will fit together properly when the whole piece of armor is assembled. The inside of the piece of armor will have "trenches" on the inside of the joins which you can fill it with some hot glue when the entire piece is assembled.

- With sharp corners in Pepakura Designer it is best to just separate the piece into two pieces and glue them together with my methods above.

- Cutting angles in a piece after cutting it out straight is a real pain and waste of time. Just cut the angles in as you go. Your hand will get used to cutting angles and you will get more consistent with practice.

- The same applies to making duplicate pieces by hand. It'll never be perfectly replicated, but just practice and practice again. I've made many failures but I've gotten better at it over time. Don't get discouraged.

- DON'T USE HEAT ON FOAM TO CUT IT. It can cause health issues. I don't want to imagine what gets released into the air when you burn the foam to cut it. Use a regular xacto knife or a utility knife with snap off blades.

- KEEP BLADES SHARP. No joke, dull blades make nasty looking foam cuts and more seam work.

- For sealing, use a heat gun to go over the prop/armor and wait till the foam changes color/texture. It will become slightly more glossy. After this, use either plastidip or mod podge. NO BONDO. Bondo does not flex and will not be good on foam. Plastidip will leave pieces fairly flexible, while mod podge not so much. I used 5 thin layers of mod podge on my iron man suit and it turned out great. Use a foam brush to reduce brush strokes left behind.

- For painting, do whatever you want. Start with either black or grey, then work in layers from the bottom up. I use acrylic paints and spray paints on my foam armor.

Above all, don't get discouraged. The awesome thing about these forums is people can help newcomers figure out issues and make it easier for new people to enter the world of costuming. Keep at it!

P.S. Foam is awesome, but I'm biased.