For this Halloween I created a sword for my Cassandra (Dragon Age Inquisition) costume. Here are the steps I took to make this sword. I have made other items out of foam in the past for art and design classes.
- Cut out of foam, carve, and sand
- Cover in drywall spackle, sand, and repeat
- Spray paint
- Paint on finishing touches
Step 1 | Plan
Before you start cutting up foam, you need to know what you’re making. Do your research, have your measurements, create design drawings (if necessary). Remember the old adage: “measure twice, cut once.” Once you have removed material you can’t stick it back on as easily.
Materials: Ideally the really dense blue foam Industrial Design students get to play with. With a deadline in mind I didn’t go searching for it and bought the pink stuff from a hardware store. The pink stuff is less dense so it’s less structurally sound. It will break easier and you can’t add as many details. But it will also cut easier and weigh less. Don’t use the white puffy stuff, it’s just not strong enough.
Here is my block of pink foam with the sword outline drawn on:
In this photo you can also see my bokken which I was using for reference.
Step 2 | Cut out of foam, carve, and sand
Cut out the basic shape with metal ruler and a utility knife.
Tips: Always use a sharp blade. Also, keep a cutting mat under your foam – it’s best not to cut up your flooring. Don’t try to cut too deep at once. Many passes is better.
Safety tip: Watch were you’re fingers are in relation to the blade. Never have them on the wrong side of the ruler. Any design student has experienced a few close calls were they almost cut off part of their finger. Also, the blade might brake/snap while you are using it. Wearing safety goggles will stop a break away piece of razor blade from flying in one of your eyes.
Next, carve your block-like sword into an actual sword shape. Again, keep a sharp blade, and be careful to not cut yourself. Then use sand paper on a sanding block to refine the shape. I recommend a harsher grit (60 or 100) to remove a lot of material quickly.
Step 3 | Cover in drywall spackle, sand, and repeat
Now you have a pink sorta-sword. Why not just paint it? If you just paint it, it won’t look good. All the foam texture will still be there. Some spray paints can dissolve your foam, so you want a nice thick layer of spackle to protect the structure. The goal is to get the surface to be smooth, so that you can make it look like it’s not made from foam.
I like using DryDex for my spackle. I like it because it goes on pink and drys white – so you actually know when it’s dry. Approximate dry time for a thick layer: overnight.
After it’s dry sand it. Start with a harsher grit to remove extra lumps and such fast. Switch to around a 150, then 220, and maybe even up to 300. The finer the grit the more smooth you can make it. Be wary of re-exposing foam. You’ll need to re-spackle and sand any area were you have imperfections or the foam showing through.
Here you can see the sword with freshly applied spackle (left), and dried spackle (right, with bonus cat):
Sorry, no sanding photos. Sanding spackle is very messy. I recommend doing it outside or in a workshop because the dust gets everywhere.
Step 4 | Spray paint
Start with a primer spray paint and when spraying an object, apply multiple thin layers, not one thick layer. If you spray on thick, the paint may crack from not drying all at the same time, and you may also get drips that you can’t fix without redoing a lot of work.
Stop and start spraying off the object. This will also help you avoid paint blobs and drips.
Safety tip: Wear a face-mask. Not one of those one-string (pretty much decorative) face-masks. Two strings, with a metal bit on the nose. Not having a proper seal will just make you breath in the stuff harder. When you put on your good 2 string face-mask, bend the nose piece, and check for air gaps and adjust accordingly.
Let dry between coats, and sand between coats with a 240-300 grit sandpaper. Why? To remove those spray edges (that you feel when you run your hands along your newly spray painted sword), and to give the next layer a good base to stick to.
Step 5 | Paint on finishing touches
Finally, you may want more detail on your sword then you can spray on. I find that using straight matte acrylic gel will stick to the spray paint and give acrylic paint something to stick to – if that’s also what you’re using.