Swimming with a Mermaid Tail – Cosplay Tutorial
- acrylic Sheet
- pencils, pens, markers etc.
- flexible measuring tape
- swimwear or vinyl fabric for tail body
- swimwear fabric for fin
- thread (make sure it matches your fabric choice(s))
- sewing machine
- sander and/or sandpaper
- hot glue gun (high heat)
- spray paint
- clear acrylic spray
Step 1: Make your pattern
The first thing you’ll need to do to start making your tail is to draft your pattern. To do this, you’ll need to take a ridiculous amount of measurements of your body. You want your tail to be as form fitting as possible, so the more measurements, the better!
First, using your flexible measuring tape, measure along the side of your legs from the point where the tail will start around your waist to your ankles. Use this measurement to draw a straight line down the center of your paper (center red line in photo). This will be the center line of your pattern. Next, you’re going to make the pattern for the front of your tail by measuring across the front half of the circumference around your waist, hips, and legs at every two inch point down from your waist. For every measurement, draw a line perpendicular from the center line at each two-inch mark (the pencil lines). You may want to measure at every 1-inch mark around your knees just to make sure the pattern will fit tightly there. Repeat this process for the back side of the pattern, with the only change being that you measure the back half of the circumference instead of the front half.
Last, draw a curved line along the edge of the lines you’ve just finished drawing to make the sides of the pattern (the curved red and green lines). You can see in my photo I’ve actually only drawn half of each side of the pattern rather than drawing two full-sized pattern pieces (the red half is the front and the green half is the back). To do this, you just need to cut your half-circumference measurements in half and only draw on one side of the center line. The arrows on my pattern point to the center of the pattern. When you go to cut your fabric, you’ll just need to line those arrows up along the fold of the fabric to cut your full-sized piece.
Step 2: Modify your Monofin
Depending on the monofin you have, you may want to modify it. You can use the monofin as is if you wish, but I feel modifying it will end up making the fin look better in the end. Plus if you modify it you won’t be limited to the shape the monofin came in. You can change it to look however you want!
To start with, I wanted to get rid of the strap that held the fin to my feet. The strap didn’t stay on well to begin with, and it was too clunky to be hidden well under the fabric I would make the tail body out of later. The first thing I needed to do was remove the knobs the strap hooked onto. To do this, I simply cut them off with my Dremel.
I also used my Dremel to sand the surface smooth.
After that, I drilled a small hole where the knob used to be, also using the Dremel.
My fin also came with some raised, rubber details on the bottom. These details would also show through the fabric, so I removed them as well. I simply cut them off with the Dremel, and then sanded the surface slightly.
I was also not happy with the shape of my monofin. Mine had a very noticeable curve to it. This curve made the fin look very odd once it was covered in fabric, so I decided to cut the entire fin section off the monofin and only keep the foot section to use. Cutting the entire fin section off may make it seem useless to have even started with a monofin in the first place, but if nothing else, having the foot section was extremely convenient and honestly worth it.
Before I cut the fin off, though, I used the fin to draw a pattern for how the new fin would look. I used it to get the shape right, and then extended the end to look more like the sort of fin I wanted. Ignore the fact that my fin has been painted white. You do not need to paint it at this point.
Then, I used that paper pattern to draw the shape onto a sheet of plexiglass. I do not remember exactly the thickness of the plexiglass, but it was thin enough to flex slightly. Plexiglass can be cut a number of different ways, but I recommend using your Dremel. It is, in my opinion, the easiest to do and the hardest to screw up. Once the shape was cut, I sanded the entire surface down, front and back, with a sander. The sanded texture will give things like paint and glue a better surface to stick to. I also sanded the edges to make them smooth.
Now it is time to glue your foot pocket to your new fin shape. There’s no special secret to doing this. Just apply a large amount of glue to the surface, press the foot pocket into the glue and let it cool. Last, paint the whole thing with spray paint. I used white because white would blend in well with my choice of fabric. You can use whatever color suits your needs.
Once the paint is dry, add a new strap by stringing a strip of spandex fabric through the holes you drilled earlier, pulling it tight, and tying the ends into knots. I used a nude-colored spandex for this, but you could also just use a strip of the fabric you plan to use for the tail or fin. Whatever you use should ideally not be able to show through the tail fabric when you’re done, so using the fabric you plan to use for the fin is a very good option.
Step 3: Make the tail body
Back to your pattern! Its almost time to cut your fabric for the tail body, but before you do that make sure you’ve added a seam allowance to your pattern. I usually use a 5/8 inch seam allowance. Yes, your fabric will stretch, but its much better to have too much fabric to start than too little, so go ahead and add that seam allowance to be safe. To be extra safe, I added a couple of inches to the top of my tail just to be sure it would sit high enough on my body. You can always take the tail in later if it ends up being too big. Once you have your seam allowance added, cut the patterns out. Yours should look as mine do in the photo below. Remember, you don’t need to add a seam allowance to the center line. Leave that line as it is and only add the seam allowance to the outside edges.
Next, its time to take a look at your fabric! You will need to use some sort of 4-way stretch fabric. I recommend using either a swimwear fabric, dance-wear fabric, or 4-way stretch vinyl. Whatever you use, you need to make sure it is a 4-way stretch and that it will handle being in water well. You also might need to prep your fabric before cutting your pieces out, depending on what kind of fabric you’re using. I used a 4-way stretch vinyl for my tail, and since the vinyl was completely smooth, I wanted to add a bit of texture to it. If you’re using a swimwear or dance-wear fabric with a fish scale pattern, or you simply like the look of a smooth tail, you don’t need to prep it at all. However, if you’re using a solid fabric, you might want to add some texture to it to mimic the look of scales. I added a large diamond-shaped pattern to it by sewing it in. To start the diamond pattern, I measured out and drew the lines for the diamond pattern onto the back of my fabric. Remember, if you do this, you need to do it BEFORE you cut your tail pieces out of your fabric. If you try to cut your tail pieces and then sew the pattern in, your pieces will end up shrinking from the lines you sew and will not fit the pattern anymore.
Next I folded the fabric over along one of the lines I drew so that the right side of the fabric was touching itself, and I sewed a straight line about 1/8 of an inch from the fold. I repeated this for every line I drew onto the fabric.
Please note that when working with stretch fabric of any kind, you need to use a stretch stitch when sewing. I use a straight-stretch stitch, but you can also use a zig-zag stitch. The straight stitch works well here. It also helps to stretch your fabric slightly on both sides while sewing stretch fabric. This allows the fabric to stretch more easily once its sewed. Here you can see what my fabric looked like front and back after sewing over every line.
Once all that is done, you can finally cut your tail pieces of of your fabric! Just fold your fabric in half, line your patterns up on the fold, pin it, and cut your pieces out! If you are using vinyl like I am, be careful not to poke a pin through where it will be seen. Instead make sure that you only poke pins through inside the seam allowance where they will be invisible or cut off completely.
Next it is time to sew the front and back of the tail together. Start by basting 5/8th of an inch in (or whatever measurement you used for your seam allowance). Basting it will make it easier to take the stitching out if you need to later. Now, try the tail on. It is at this point that you will be able to see where the tail needs to be taken in. Stretch the fabric a bit as well to make sure the tail will be form-fitting. After you’ve marked where the tail needs altering, take the tail off and resew along your new lines. Try the tail on again to make sure it fits correctly. If it still needs changing, change it now. If not, go ahead and stitch the tail together with a stretch stitch and trim the edges. You can also hem the waistline of the tail at this point.
Step 5: Cover the fin with fabric:
If you modified your fin, you can use the pattern you made earlier to cut out the fabric for the fin. If you did not modify your fin, make a paper pattern for the fin now. All you need to do is trace the shape of the tail out on a piece of paper and add in a seam allowance. Use the paper pattern to cut out the shape of your fin fabric.
I used both a swimwear fabric I dyed to a very light blue and a swim mesh I also dyed a slightly darker light blue. I used the swimwear to cover the fin first, hiding the monofin, and then I used the swim mesh over that to give the tail more texture. Sew the fin fabric together at the sides using a stretch stitch, but leave the top and bottoms open. If you’re using two layers of fabric like I did, slip the inside fabric inside the outside fabric. Then, sew the fin fabric to the tail body by turning the fin fabric inside out, slipping it over the end of the tail body, and sewing around the end of the tail. Your fin fabric is now attached to your tail body! Now you need to install your monofin. This is actually quite easy. Just take your monofin, fit it inside the fin fabric, and wiggle it into the tail body a short amount just so it sort of secures itself in place. You want part of your tail body at the end to cover a bit of the foot pocket on the monofin.
Now, all that’s left is to sew the very bottom of your fin fabric together so it doesn’t slip off. To do this, I simply pulled the fabric tight and used my sewing machine to stitch along the fin as closely as I could. Your tail, however, may not fit entirely through your machine. If this is the case, just sew as far as you can and then hand stitch the rest closed.
Once that is done, trim the fabric fairly close to the stitching line. I left about 1/4th of an inch on mine just to be safe.
And with that, your tail is done! If you left your monofin in tact, you’ll actually be able to swim in your tail! Only attempt this if you are an experienced swimmer though. Swimming in a monofin is not the same as swimming without one and can be dangerous if you don’t know what you’re doing. If you’ve altered your fin as much as I have, and the only thing holding the foot pocket to the fin is hot glue, I would not recommend trying to actually swim in it. At that point it’s only there to look pretty, not to be functional.
Now go put on your tail and be a majestic, beautiful mermaid!