Cosplay Tutorial: Fionna’s Crystal Sword (The Cheap Way)

Hey everyone, I’m excited to bring you my first ever cosplay tutorial. I hope you find it helpful and if you have any comments or questions be sure to ask.

For Anime Fest this year I wanted to add a prop to my Fionna costume that would be inexpensive and quick to make since I only had two weeks to do it. After debating between a Cake plush and a Crystal Sword the sword won out in the end for it’s super low price point. Can’t beat a sword that costs less than $20! To make this prop cheaply I used primarily foam core. Since the sword is so geometric in shape foam core works well. This will not work for swords that are not straight (like a Katana or anythings else curved) but could be adapted to make other sword types like a broadsword.

Materials:

Foam Core (I used 1 sheet 20″ x 30″)
Expanding Foam
Handle Base (I used a wiffle ball bat)
Craft Foam
Wood Glue
Sand Paper
Spray Paint
Clear Coat
Paper Clay
Xacto Knife
Hot Glue Gun

Optional:

Styreen
Craft Acrylic

Before we begin I’ve made this little diagram that labels all of the parts of the sword. I’ll be referring to these parts by these name so please use this as a reference if you are not familiar with some terms.

Cosplay Tutorial

Step 1:

The first step is to figure out how large your sword it going to be. Use your reference images and your overall size to determine the size of your sword. Once you know how long to make it you can start to figure out the size of individual pieces. I decided my sword would be about 32 inches long. Once I had that measurement I figured out how long to make the blade, the point at the end, the handle and the pommel. After deciding the length you need to also decide the width. My sword blade is 5 inches wide. You can make a pattern on something like tracing or craft paper if you need to see the size before cutting your pieces.

Step 2:

Next we will cut out the blade. You will need two pieces that you will score and fold to create the three dimensional shape. For this I cut 2 pieces that were 20 inches long and 5 inches wide. Once you have cut those out you will need to score them down the middle with your blade. You want to make sure to cut through the first later of poster board and the foam, but not the second layer of poster board. This way you can fold the pieces to create the proper angle. After folding you will need to angle the cut edges so they can be glued together. Angling the edges allows for a more seamless edge. Take your Xacto blade and slice at an angle of about 45 degrees. It doesn’t need to be exact. After cutting your angle use a high grit sand paper and sand the edges down. Remove the dust and you are ready to attach your pieces. Attach the two pieces together using hot glue. Make sure there are no gaps or unsealed areas because later we will be using expanding foam. Once your pieces are attached you should have a box with a hole on each end. One of these ends will receive the point, the other will be where you set your handle with expanding foam.

Step 3:

Add the point to one end of the box. This step is a little trying because it either requires math (which I don’t do very well…) or guesstimation. The key is to have 4 triangle pieces that will come together to make a point. It can be a little sloppy because we will be filling in any gaps with clay to smooth out imperfections. You will need to make sure the triangle pieces have the edges angled like we did before for the box edges. Once again make sure any gaps are filled with glue. It can be helpful to use a sheet of paper to create test pieces to get the shape right.

Step 4:

Once the point is added it is time to set the handle. Using your handle base you will place it into the box and make sure it sits center and straight. I did this by creating a grid of masking tape to hold it on all sides. Masking tape works well because it is easy to remove from the poster board once this step is finished. After you have your base situated you will need to spray expanding foam into the sword. Expanding foam will create more strength and hold the handle base in place. Because the foam expands you do not want to fill the sword. I filled mine about half way and that was perfect. Let it sit overnight (or at least 6 hrs) before continuing to the next step. I chose at this point to shorten my wiffle bat so I cut it using a Dremel starting at the textured handle. This is not something manditory for all handle bases. If you do choose to use a wiffle bat as a base there is a texture and a nub at the end of the bat. You can either cut this off, or use the bat in its entirety if you don’t mind having a round pommel on you sword.

Step 5:

Before we can beging the finishing process we need to add the hilt of the sword and the pommel. For the hilt we will be using more foam core, but for the pommel I used craft foam and styreen. For the hilt we will need 6 pieces, 2 diamonds (one about a half inch smaller than the other on all sides) and the 4 sides. You want the larger diamond to sit against the sword blade and the smaller one to sit below so that the hilt is angled in towards the handle. To figure out the size for both pieces I used a sheet of paper to make a quick pattern, cut a hole and slipped it on to see the sizing. Once you have constructed the hilt you will slip it onto the handle base and glue it to the open end of your sword.

For the pommel foam core would have been too thick so I switched to craft foam. I cut two diamond shapes and glued the bottom points to the sword, parallel to each other and the tops together.  You want it to taper into a point at the end. I then used more foam core to fill in the sides, simply glueing a piece down and then trimming it to the correct size. If you do not want to use styreen for this next part you can just seal the craft foam with wood glue from the next step. If you do have some styreen you can cover the foam with the styreen to create a paintable surface.

Step 6:

It’s time to begin the finishing process! First you want to give all of the poster board (and and exposed craft foam if you have it) several coats of wood glue. Why? The wood glue is going to add strength to the poster board and help fill in any small holes or imperfections. I gave my sword 4 coats. You don’t have to wait until the glue is fully dry between coats, I usually wait until it’s touchable without being tacky before I’ll add another one down. Usually it takes and hour or two between the coats. After you apply your last coat you will want to wait until the glue is fully dry to continue on to the next step.

Step 7:

Next we need to fill in any imperfections with paper clay. Paper clay is an air dry clay that is super easy to work with and smooths out very well with a little water. It’s great for filling in imperfections. On my sword I filled in any gaps along the glued seams as well as making certain parts level. I had some fairly large gaps up at the point that I was able to smooth out using the clay. The other great thing about paper clay is that is is easy to sand so don’t worry about making everything 100% perfect. You will be sanding to smooth it all out before painting. You will need to let your clay dry, it usually takes between 6-8 hours so play accordingly.

Step 8:

SAND! Sand the whole thing down. Start with a medium to fine grit and move on to an ultra fine grit. You want everything to blend together so that it looks like one piece. After sanding you should take a damp cloth and wipe down the whole sword.

Step 9:

You’re almost done, all that’s left is painting. I used a primer coat and then 3 coats of a fluorescent pink spray paint. I WOULD NOT recommend the fluorescent paint, it was horrible to work with. It says it has a 15 minute dry time but what it really means is in 15 minutes it will feel dry to the touch but turn into a sticky tacky mess if you actually try to hold it. It also showed off any imperfection. I would recommend using a regular gloss or matte color. This next step if optional, I decided to paint the handle of my sword with a slightly darker metallic craft acrylic. This just gives the sword a little extra dimension but if you don’t want to do this or don’t have craft acrylic already at your disposal you can just skip right to the next step. After painting you will want to apply 2-3 coats of a high gloss clear coat. This is going to give your sword that super shiny crystal look. Always make sure you wait until coats are completely dry before applying the next one.

Cosplay Tutorial Progress Photos

And there you have it, a super pink and shiny crystal sword just like Fionna!