Quick and Simple(ish) Way to Make EVA Foam Knight's Helmet

I'm going to a 60s garage festival and they have decided to give it a Medieval theme this year, woo-hoo! So I'd finally be able to make myself a Norman knight outfit. I spent ages trying to figure out how to make a pretty reasonable helmet. I made 4 separate prototypes until I got it fairly reasonable. I even tried some maths. If you want to make yourself a helmet and want short cuts, you've come to the right place. Mine is Norman/crusader style.

Materials

EVA foam. I used 5mm (about quarter inch). I initially used an old yoga mat for the prototypes and this was okay, but I decided to use proper stuff for the finished item.

2mm EVA foam for the banding and nose guard. It looks good and I also wanted the nose guard to be very flexible so that I can drink pints without it getting in the way...

Dome head pins for the rivets.

Contact cement. I used evo-stik brand (UK) but I imagine most of them will do nicely.

Paper and cardboard for test runs.

Primer paint (I used white primer for water based wood paint as I had some for skirting boards. Worked fine).

Paint. I used acrylic paints, silver, gold, black, crimson and brown.

Tools:

Scissors. I found scissors worked better than an exacto knife for cutting EVA foam.

Sharpie or similar.

Tape measure

heat gun

Something more or less kind of sort of bonce shaped to heat form.

This is a gore. I had never come across one before this week. They are amazing. You use them to turn a 2d thing into a 3d shape. In this instance 4 gores of this shape will make a helmet. There are gore calculators online, but they are painful if you are mathematically challenged like me. So I set about figuring out the shape and size of the gore I needed.

I made a crumpled silver foil hat to fit my head then cut it into quarters to get a rough gore shape. Then made guesses and prototypes out of paper then yoga mat pieces. No, wait, you don't need to do that. Here's the shortcut:

1. Measure around your head where you want the bottom of the helmet to be. Divide this measurement in 4.
2. Print out a picture of this gore. Resize it until the bottom of the gore is the number above. Cut it out and trace it onto cardboard for a better template.
3. Use the template to trace and cut out 4 gores from paper. Stick them together and see if it looks kinda right. If not, adjust. If it does look right move on to cutting the the eva gores.
4. Cut 4 strips of the 2mm eva to cover the seams. About an inch wide.
5. Cut a T shaped piece for the noseguard that looks about right to you.

If you want to change the pointyness of the helmet, make the top of the gore more or less pointy. A 90 degree angle would make the top of the helmet completely flat. I didn't go too pointy as I'll be watching bands in mine and didn't want to block people's views.

Time to get sticking. I didn't take any photos of this stage, but there's plenty of online help. It's pretty easy. Glue is stinky and probably nasty, so have ventilation and preferably a mask too.

Before you stick, number the gores and make registration lines to make your life easier when gluing. See those short horizontal lines on the blue prototypes? They are registration marks. They make your life easier when gluing so the pieces line up properly. Hold piece 1 next to piece 2 and draw some lines. Etc.

With contact cement, spread glue down both sides to be joined and wait for a couple of minutes until both surfaces are only slightly tacky then join firmly and carefully, following your registration lines.

Do the same again to glue the strips and nosepiece on.

Wait 24 hours for the contact cement to fully do it's thing before applying heat.

Use a heat gun or blowtorch (careful now) to gently heat your helmet (it IS now a helmet isn't it?) then press into a more nicely rounded pleasing shape. I used a large round aluminium jug to press onto. Don't go too mad, gentle heat will work. Make sure you do this somewhere ventilated and preferably wear a mask.

This heating not only shapes it, but apparently makes it better for accepting paint.

Prime. I saw lots of suggestions to use proper foam primer paints. They were expensive and I didn't have any. I am both impatient and cheap; two good reasons to try something else. I had some 'Acrylic Primer Undercoat' for painting woodwork. It's £18.99 for 2.5 litres in the UK and did an excellent job and is very flexible. Gave it 2 coats. Dried in no time.

Two topcoats of acrylic silver paint.

Paint black acrylic paint where the bands join and a few light scrapes here and there. Use the dry brush technique where you dab the paint off the paintbrush so that only a small amount is left. I also put some crimson and brown dabs to represent rust.

I sprayed some clear coat on top as it gave it a bit of shine.

And finally for the rivets. Cut most of the pin part off of some dome head pins, sand the shine off, glue them on.