Introduction: Foam Sword Props
I love swords. They just have so much style and character. To appropriate a quote from Jedi Master Obi-Wan Kenobi, They're an "elegant weapon for a more civilized age". Or at least that's how I like to think of them anyway.
The problem with swords is that they can get expensive and they're not exactly "safe" to carry around everywhere, which is a problem if you've decided to dress up for Halloween or a similar event and you're character has a sword. Many conventions don't allow real swords (or even hard wooden swords) and when trick or treating or going to a costume party the more responsible option is a fake sword (especially if there will be drinking at the party).
So, what do you do if the character you're dressing as has a very specific weapon and there are no toy versions available commercially or it's too expensive?
You make it out of foam board of course!
Step 1: Supplies
The main ingredient of this prop is obviously foam board, specifically extruded polystyrene, or insulation foam board. This comes in several flavors. The most popular option that I've seen seems to be "Pink board", which is Owens Corning brand, but you can use DOW blue board or Pactiv green board. For our purposes it makes no difference.
It also comes in different thicknesses, so you can buy whichever thickness is most appropriate for your sword. Depending on the thickness you get you're probably looking at spending about $15-30 per board, but they come in 4'x8' sheets so you can make tons of swords!
Tip for those more frugal prop makers out there: If you only need the one sword, find some friends who need costume weapons as well and split the cost. Or check with local builders or suppliers to see if they have any damaged sheets they might be throwing away or selling for cheap.
Aside from the foam you will need:
-A Saw (very fine-toothed)
An Aside: For this particular sword I used some scrap foam I had on hand and had to glue two pieces together. If, for any reason, you have to do something similar be careful what kind of glue you use. You need something pretty heavy duty, but certain glues can eat away at the foam. The one I used is some construction adhesive I had on hand called QB-300 but I'm sure there are other things out there as well.
Step 2: Design
The sword I made was from the anime The Qwaser of Stigmata. I started by looking up reference material for the sword (of which there is an unfortunately small amount). Then I drew it a couple different ways to make sure that I understood the shape and how to transfer it to the foam. Once I thought I had it down I just free hand drew it on to the foam (I did use a yard stick to get straight lines). If you don't want to chance it or you want it to be really precise you could print out a picture in sections and trace it onto the foam.
Step 3: Cutting It Out
For this step I actually used a key hole saw because it has fine teeth on it, the teeth are all straight instead of sticking out to each side like some saws, and the smaller blade allowed for more detail. I also used a coping saw to get the curve underneath the handguard.
I've heard of some other ways but unless you want to get really fancy this works fine.
I'll borrow a line from Phil of Modern Family here and say, "Slow is smooth and smooth is fast." This foam crumbles apart pretty easily if you're not careful so if you want a good clean line use slower smoother motions than you would normally use with a saw. In fact, before you cut out your sword you might even try sawing on a corner you won't be using to get an idea of how it cuts.
Like I said before I was using scraps, so my foam was actually a lot thicker than I wanted. To remedy this I started by cutting it in half. then I just carefully cut it out.
Once it was cut out I needed to "sharpen" the blade. To do this I drew lines to show how deep I wanted the angle of the blade to be and another line down the side for the edge. Then I used those lines as guides and sawed the edges off. I got a little over eager here and you can see where my cut was a little wavy near the base of the blade.
Step 4: Smoothing It Out
No matter how careful you are with the saw the cuts will at least look pretty rough. To fix this I just sanded the whole thing down with sandpaper. I started with a medium grit sandpaper and smoothed everything down and rounded all of the edges. This is also where you'll want to give it any detail. This sword didn't require much detail but it just looked so plain that I had to do something. I actually just used my sandpaper to sand down the foam a bit and leave a ridge going along the guard. It's hard to make out in the picture but it starts at the blade and goes to the bottom of the guard.
If you need more detail than that there are plenty of ways to make it happen. Files would work well, or a dremel. The foam is soft enough that you could probably use tons of things that wouldn't work on harder materials. You can also attach plenty of things to it.
Once you're done any detailing just give it a quick sanding with a fine grit to get it nice and smooth.
To anyone like me who hates sanding: Don't worry, this isn't super tedious. The foam sands very quickly.
Step 5: Painting
Before I talk about painting I want to add that if you want a really fantastic looking prop there are various finishing techniques you can use first that will help give you a more professional look. I left this one as plain foam but you could probably use paper mache, or you could use an auto-body filler like Bondo and give it a really smooth realistic finish.
Foam is pretty sensitive to chemicals so you have to be careful with how you paint it. First off, do not use oil based paints against the bare foam. It will eat into it. Secondly, even if you use acrylic spray paint it can eat into the foam if you spray it on too thick. If you choose to use spray paint just apply it in very thin layers. You could also paint a primer on first which would give you a nice base layer to work from. Then you wouldn't have to be as careful when painting it.
For this sword I didn't bother with anything fancy because it's just red. I tried to spray paint it in thin layers and for the most part that worked out... until I got impatient. But that's mostly just on one part. After I spray painted it I dry brushed some black acrylic paint into the detail so it would stand out a bit more.
Step 6: Finished
Before I go I should add that while this is sturdy enough to carry around as a prop, if you tried to use this sword to fight it would snap in half pretty quickly.
So there you have it! That's how you make a foam sword. Now you can have a pretty inexpensive and incredibly safe prop next time you want to dress up as your favorite sword carrying character. I wish I had a better picture of the finished product, but this was for my brother-in-law's cosplay and I was in such a hurry to get it finished for him I somehow forgot to take a "completed" picture. Doh. I was able to get this quick cell phone picture texted to me at least but I still feel pretty stupid.
I hope you enjoy this and have fun making all kinds of swords!