How to Make a Knights Templar Cosplay Helmet - Step by Step - With Photos

I received a couple of inquiries about exactly how I make my cosplay Knights Templar / Crusader / Great Helm helmet out of old discarded Coroplast® real estate or election signs. Since it was raining this weekend I figured I would make one and photograph the process. If you read through these instructions and have any specific questions please let me know.

This is intended to be a rough guide on how to make a Templar Helmet from old plastic. The measurements shown are the ones I used for this build. You will have to adjust things for your project.

Keep in mind that I figure this stuff out as I go, and kind of wing it. In the back of my mind I know things that are too long, or short, or crooked, can always be cleaned up/fixed later. If not then I can always start again.

Remember you are creating something cool out of other people's trash.... Have fun with it.

These are the tools I use to make all my Coroplast® projects including this helmet. Hot glue gun, Pencil (from mini golf), utility knife/box cutter, and a ruler. For this project you also need some masking tape, large and small drill bits, paper fasteners, and a little paper towel. Everything you need is really simple, and very inexpensive.

For this project I needed one more thing, some wire. The first problem to figure out is how big to make the helmet. Rubber planter wire from the dollar store is perfect to solve this problem. You can use a coat hanger, but I like the pliability of the rubber wire.

Take a piece of wire and make a loop that fits around your head. Ensure the wire doesn't touch your nose, nor fold over your ears. This loop will be the the inside diameter of the helmet. If you make the loop too small your nose will be squished. If it is too big the helmet will fall off when you look down. Don't worry if the size isn't exactly right. You can add or remove pieces later to make the size comfortable. It is much easier to cut out pieces and make the helmet smaller, so a little too big is preferable.

Once you have the loop sized, fold it exactly in half and measure the length. half of my wire is 13.5" (I have a big head). We use this number to make the bottom portion of the helmet, which we will do in two pieces. In my case two pieces 13.5" long.

Draw a 13.5" straight line, perpendicular to the ribs/rows of plastic. The ribs need to be up and down so it will be easier to curve the helmet. In the middle of this line we will add a bump out for the chin guard. From the middle of my 13.5" line I measured down 2" and 4" in each direction. I like a curved chin guard so I use a dinner plate to make the curve between the two spots I just measured.

Wow. That pencil is hard to see, isn't it? From here on I will go over everything with a marker so it shows up better in the photos.

There. Now we can see the lines better with the marker. Here is the layout of the helmet bottom. The distance from the corner of my eye to under my jaw is about 4" so I made the pieces 4" high. You can make yours whatever height you like. My head is shaped more like Dr. Bunsen Honeydew, maybe yours is shaped like Beaker.

Now the pieces for the bottom portion are ready to be cut out.

Whenever possible I try to have the top edge of these pieces run along the cut from the factory. I didn't do it this time, and it isn't critical, but using the factory edge ensures bottom portion is 100% straight. Be as precise as you can with the cuts on the chin guard since it will be right in front of anyone to whom you are talking. Now we need to make these pieces curve around the head.

On the side of the plastic you want on the interior of the helmet, cut down each of the rows from top to bottom so the pieces can be curved. Leave five, or so, rows at each end of each piece uncut. This will help flatten out the sides of the helmet. Charlie brown is the only one I know with a round head, so a little flat on the sides is important.

Tape the pieces together and slide them over your head. If they fit the way you like, line up the front and back pieces and glue them together. These seems are the exact sides of the helmet. Knowing this helps later when installing the trim and lining things up.

If you glued it properly, flip the bottom portion over and it will sit flat on the table. Now is a good time to make sure it is exactly the size you want. Everything else you do will be built off of this base. Try it. Cut a piece out, or add a piece in as needed. I you need to add a piece in I would recommend adding it to the middle in the back. That way the patch will be hidden when we add the trim piece later.

Making sure the rows are up and down..... My bottom pieces were 13.5" long each, so I will make my top pieces 14" (better to be long than short). Mark the middle of the top piece, in my case 7". The distance from the corner of my eye to the top of my head is about 5" so that is how high I'll make the top. Now we have two pieces drawn out that are 14" long and 5" high. We are going to make the top out of four pieces so cut the pieces you just made in half where you marked the middle.

We need to guess at making the curves, and fitting them together. Usually this is where the swearing starts.
We have four pieces that are 7" x 5". On each piece measure 1" from the top down, in the middle. Measure 1" up at both ends. Using a plate, serving plater, or just guess, mark curves to the spots you measured as shown above. It should look like a sagging bridge when you are done.
Just like with the bottom, cut down each row on what will be the inside of the helmet. Cut down through all the rows this time, there aren't any flat spots.
Once the cuts are made glue the four pieces end to end. Make sure one end is open and it looks like a big crooked 'C' when you are done.

Cut and skin 6 reinforcement tabs, 1" x 3". These will help hold the top and bottom in place securely when you start assembly, plus they are used to mark the eye holes.

The 1" x 3" tab from above is the same size as the eye holes. Hold the tabs were you want the eyes cut. Trace the tab, then cut it out. Works like a charm.
Next, glue the tabs into the bottom portion of the helmet. Add one front, back, each side, and on the outside of the eye holes. Put the tabs in the center of the seams and keep them straight. On top of adding support to the project they will help you keep things lined up.

Set the top portion on the base to make sure it lines up and is straight. Make adjustments as you go. Remember you can add or remove as much material as you want. However, if you are way off you may want to start over from scratch. This is the only part of the build that is a real pain in the butt. Trying to gett the curves on the top right so it will match the base can be frustrating.

Flip the helmet upside down. It is much easier to dry fit the pieces if the top is against the table. Dry fit the top to the base to make sure everything fits. And it looks like the piece I made is a little too big. It is close, but since this isn't horseshoes or hand grenades close isn't good enough.

Well the size was pretty close. So this will be an easy fix. I'll remove one row and try it again. If it doesn't fit then I'll remove more until it does.

Great one row was enough. The top portion is now the correct diameter to fit on the base. Connect the ends of the top portion together. If it looks like a flower pot you did it right. In this case the top was too big. If it is too small you can just add pieces rather than remove. Once you are happy with it glue the loose ends together.

Because the helmet is flatter on the sides it is really tough to make a top that will just drop into place without some fitting. Flip the upper portion back over over and you will see it doesn't sit flat on the table. But there is an easy way to fix that problem.

Wile holding the upper portion of the helmet down on the table. Lay a marker or pen on the table with the tip touching the plastic. Keeping the marker flat on the table draw a line around the helmet. Cut at the line and the upper portion now sits level. Almost done. Flip the helmet over and do the same with the top. After you clean up the top measure the size of the opening for the top piece/lid.


In all honesty I didn't forget. I skipped this step. I have made so many of these helmets I didn't even think to dry fit this one. Sorry 'bout that. 

Before you start gluing piece together, we have to make sure this thing fits. Use masking tape to dry fit the helmet together. Try it on. Now is your chance to add, or take out, pieces to make the helmet fit properly. Look in the mirror, from the front and side. Make sure it looks how you want it. Once you are happy with the fit, and the look, glue the top to the base.

After we made the top portion sit level, measure the size of the opening. In my case it was 6" x 5", that will be our lid. Cut out a 6" x 5" square to start. We measured in 1" on each of the 4 pieces we cut for the sides. Two pieces at 1" makes 2", so I measured in two inches in each direction from the corners. That should be close. I have no idea if that math works but like I said a the start "I figure this stuff out as I go, and kind of wing it."

After cutting out the lid I always push it into place from the inside. If the lid gets stuck you can easily see where you need to trim to make a good fit. It may take a few tries but when you are done the lid will fit tight, support the entire upper portion and look good.

Because you pushed the top in from the bottom the edges should be nice and tight. Run a bead of glue around the edge to secure the lid from being pushed in. This is the only glue holding the lid so be generous.

The exterior fit will not be perfect so have to go around everything and trim uneven edges and random squirts of glue that popped out. We are not trying to make something that looks like it came from a factory in Asia. We want rough and rustic, so a few imperfections are actually a good thing. When we put the finishing touches on, and add the paint later, these small issues will really add to the overall look. I know that seems counterintuitive, but it's true.

Now we are going to cover up all the ugly joints and crooked cuts. Cut and skin a strip 1" wide and long enough to go around the helmet.

Add a trim piece around the helmet where the top and bottom portions meet. It is a good idea to use scrap pieces to press the trim into place to keep from burning your fingers. Once the trim on, add a bead of glue to the seam on the inside of the helmet. If there are small gaps at the top when you are done, you can fill them in with layers of glue later, sort of like a 3D printer.

I like to have 3/4 of the trim on the bottom portion. I think it lines up nicer with the cross.

Because so many things were cut freehand, it is impossible to figure out how to cut proper sized trim for the top and bottom. We need to make a templates. Tape two pieces of loose leaf paper around the top of the helmet. Make sure the entire edge of the helmet is covered.

Once secured draw a line inside the paper, using the top of the helmet as a guide. Remove the paper and cut along the line. Or you can do it the lazy way and use your knife to just cut off paper while still on the helmet, until it is the right size. I guess you can tell which method I used.

When you remove the paper you will have the exact shape of the top to use as a template to make the trim.

Using the tape still on the paper, attach the template on a piece of Coroplast® and draw a line along the curved edge.

All trim pieces are 1" wide so get out your ruler and start measuring. Remember that you want to measure away from the curve. This line you are creating will be longer that the original.

Measure down 1" all along the length of the curve, making dots as you go.

After all the dots are made, and the measuring is done, just connect the dots. A perfect 1" trim piece that will fit the top of your helmet perfectly. Once it is cut out.

Now cut out, and skin, the trim piece you just made. It is ready to apply to the top of your helmet. Yes it does take a while and makes a real mess. 

To trim out the bottom you can use the paper method again. Or since you know the sides and back are a straight line you can just trace the curved bit onto the Coroplast®.

Get your ruler out and do your 1" measurements again. Cut out and skin the trim piece you just drew. It is ready to apply to the bottom of your helmet.

Now we have to cover up the vertical seems. Cut and skin three strips 1" wide and as long as the helmet is high.

Glue on the horizontal pieces first, then the vertical pieces of trim. You are using this trim to cover your ugly cuts, mistakes and to strengthen the helmet.

A Knights Templar helmet isn't right without a cross on the front of the helmet. I tried a one piece cross twice, don't bother. There are so many different angles that I just couldn't make the cross sit flat and look 'right'. The cross can look any way you like on the ends. I chose straight lines to make the plastic easier to cut. But I have seen fleur de lis, and playing card "clubs' shaped ends, we may as well keep it simple.

The vertical piece is 8" high x 3" wide at the ends. It narrows to 2" in the middle. Measure your helmet to find the exact height.

The horizontal piece is 10" wide x 3" tall at the ends. It narrows to 2" in the middle, just like the vertical piece. We are going to need to see so you will have to cut out eye holes 3" x 1".

The two pieces of the cross are now cut out and ready to go on the helmet. 

Poop! I just noticed that I messed up on this one. The space between the eyes in the horizontal piece should have been 2" but I made it 1". No problem I'll just cut notches out of the vertical piece. Just remember to make your space 2". 

Don't get upset or be afraid to make mistakes. I have made a dozen of these helmets and I just messed up during the example I am posting online. Stuff happens. Just have fun with it.

Now that it is together, and fits my head, it is time for paint. If any pieces have popped loose now is the time to glue them back down and clean up other things you see wrong. Hot glue doesn't stick well to a painted surface, so fix them now.

To paint the helmet I use whatever hammer-look silver paint is the least expensive, in this case it was Krylon. The paint on the fist helmet I made kept chipping off, even though the paint is 'primer and paint in one'. The manager of an auto body shop told me to always use an adhesion promoter when painting onto a flexible plastic. It is what body shops do before painting a plastic bumper. It made a world of difference and I highly recommend its use.

There we go with the adhesion promoter and two coats of paint. It is actually starting to look like a helmet now. The paint ran a bit behind the eye, but that is okay, boo boos like that make the helmet look more worn, old and realistic when done. 

With some paint it does look a lot more like a helmet, albeit a cheap children's Halloween costume. But, it does look more like a real helmet, so we are on the right track.

Now we get to take the helmet from what looks like a child's toy, you can get at Walmart, to something actually worn during the second crusade to the Holy Land. The technique is called weathering. If you are interested there are lots of posts, and videos, from people considerably more talented, and experienced at weathering. For our project I just use cheap, acrylic, black paint I picked up at Walmart.

We want to make the nooks and crannies [What the hell exactly is a cranny?] look dirty and worn, but we still want to see the textured metal paint underneath. There is no need to be fancy or neat with this, because the paint wont be there long. Use a brush to get paint all over especially into any edges or seems. Then rub off the paint with a piece of damp paper towel. 

Just a piece of paper towel, a little elbow grease, and presto a weathered helmet. For this helmet I used two pieces of towel dry, then a damp third one to get all the paint from the high points.

Here is the helmet with one application of black. Look at this photo compared to the the one after the original coat of paint (four above). It doesn't even look like the same helmet. After the black you can add browns, golds, or copper spots randomly to really make the weathering pop.

Now we are going to add a splash of colour [I am Canadian so the 'u' is there on purpose] and make the helmet pop. Once again I use cheapest acrylic paint I could find.

The red cross draws the eye away from any imperfections in the helmet. Plus a crusader helmet is identified by the cross on the face, so you kind of have to do it.

You need two different size drill bits. A large one to drill large air holes in the front of the helmet. Plus a smaller one to drill holes anywhere you want to place the rivets.

What do I use for rivets? I tried a couple of different things and found that these dirt cheap round head fasteners (~$5.00/100) make great rivets. 

All the holes are drilled. Now we need to add the 'rivets' and paint the air holes black. Once the holes are drilled spray the entire out of the helmet with a clear spray varnish/sealer. I added three coats with drying time in between. 

Push the fasteners through the holes and bend the ends to keep them secure. The inside of the helmet is now a mess. It looks like an old sign with a bunch of staples poking through. However....

The cheap and easy fix for the ugly inside is duct tape. Covering the inside in duct tape will: protect your head from getting scratched up by the fasteners, make the inside look metallic, and add structural stability to the entire helmet. I cover the inside in a layer of tape then cut out the eye holes.

There it is one cosplay Knights Templar / Crusader / Great Helm helmet

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