I began by making the pattern for the waistband. This helped determine how long the sequin portion needed to be as the length changed in the front/back/sides. I wrapped my dressform’s hips in plastic wrap and covered the section where the waistband sits in duct tape. I then drew on the waistband, marking the side seam and front center.
Once drawn, I cut the waistband off, cut off the excess and checked how it looked on my own body. I needed to add an inch to the back length but was otherwise satisfied. Laying the duct tape waistband on top of my pattern paper, I traced the outline and added the extra inch to the end and ½” seam allowances on all sides. Next up, I cut out two pieces of foam using the pattern and removed the ½” seam allowance from the top of each piece. These edges would not be sewn to anything. I then cut out four pieces (2 sets, right sides facing each other) from the stretch spandex, marking the seam allowances on the wrong sides with the heat erasable pen. (Most spandex can take a minimal amount of heat without damage, but test your spandex before doing this)
I sewed the top edges of each set of spandex, right sides facing each other, with the stretch stitch. You don't need to trim your seam allowance unless you have very deep curves, so I did not. I then turned those pieces right sides out and placed the foam inside. While stretching the fabric taut, I pinned the open edges closed sealing the foam inside. This was finished by machine sewing those edges closed with a simple straight stitch. The final step of preparing the waistband was aligning the front points together, sewing with two rows of straight stitches and trimming the excess.
Now it was time to start on the sequin portion! I began this by putting the finished waistband on my hips, where I'd like it to sit, and I measured from the bottom edge of the waistband at my side to the ground (shown in photo below on mannequin but it's more accurate on yourself). I then took that measurement and drew it onto my pattern paper, lengthwise. Next, I took my hip measurement at my widest point, divided it by 2 and added it to the same pattern paper, widthwise. This made a rectangle.
Taking my waistband pattern, I lined up the front center seam with the top right edge of the rectangle I just drew. I slid it down until the top of the rectangle met the bottom edge of the side hip portion of the waistband and traced that edge from side seam to front center. This accommodated the pointed tip of the waistband when sewing. Now, because my low hip and high hip measurements vary by several inches, I added a dart that reduced the top edge by 2”, which will total a 4” reduction when including the other half. I also reduced the center back by 1” (totalling 2” when including the other half) and drew a curved line from where my low hip (widest point of bum) is to the top of the rectangle. I made this as gradual as possible to avoid a “point” that sticks out when sewn.
To achieve the narrow bottom, I measured from where the waistband meets the sequin fabric in the center back to just behind my knees and made a mark on my pattern of this. I then reduced the width at that point by 5” and smoothed the transition from my low hip mark to this with my styling ruler. At this point, it's best to cut out, assemble the waistband and tail, and test that all the lengths are correct. Thankfully, when using mesh fabrics, they have a lot of stretch and shiftability so small miss-measurements are forgiven. This is why I felt confident in moving right into the sequin fabric instead of using muslin, but you can do a test with muslin if you are more comfortable.
I laid out my sequin fabric wrong side up as straight as possible and traced each half of the pattern on the back with my heat erase pen. Flipping and lining up the pattern so it formed one large shape. I used very sharp scissors to cut only the mesh backing, avoiding the sequins. To sew with sequin fabric, you MUST remove the sequins from your seam allowances and ¼” away from your seam line. It is tedious, but makes sewing so much easier and prevents scratchy sequins from rubbing on the insides of your garments. I removed these sequins with tiny snips and put them in a small jar for later use.
Once all the sequins were removed from the “danger zones”, I attached it to my waistband using clips and a straight stitch. I then basted the back center seam from the bottom to the low hip point and popped it on myself to see if I liked how it hung. It was correct so I then decided how far up I wanted the fins to start on the sides of my legs. I went with just above my knee for maximum movement. I also estimated how wide I wanted the fins to be when fully spread out. My measurements ended up being 18” from ground to top of fin and 16” wide when spread out. Which means, each fin needed to be a half circle shape measuring 18” tall and 32” wide plus seam allowance.
I cut two fins with those measurements plus ½” seam allowance out of my satin and put them aside. Going back to my paper pattern, I measured 18” from the bottom of the tail and halfway across widthwise and marked it. Then, I drew straight lines from that point to both the front center and back center bottom edges. After cutting out the resulting bottom triangle from the paper pattern, I took the basting out of the back center of the dress and laid it flat to trace the new bottom shape, cut the excess fabric and removed the sequins from the seam allowance.
Next, I sewed the center back closed and added the zipper. This went from the top of the waistband to just above the low hip point of the skirt, which was 9” for me. I ended up removing the sequins ½” from the zipper and then re-attaching a few to hide it without impeding its ability to zip.
I attached the fins I had put aside by lining up the center point of the long edge with the top point of the triangle in the skirt and sewing with a straight stitch. I then added one single line of horsehair braid to the entire bottom circumference of the skirt, including the tiny bit of mesh in the center front and back.
That's it! Phew! I know that was a long one but now you have an easy to assemble pattern for every one of your mermaid dreams! I'm already thinking of my next mermaid tail color scheme and style. You could make this even more elaborate by hand-sewing hip fins or a back fin. Even adding on strands of pearls or shells! The possibilities are endless and the removed sequins make great supplies for jewelry, crowns, hair additions and anything else!
If you use this as inspiration, I would LOVE to see the result! Please tag me on Instagram or TikTok : @seams.come.true
And, as always, I'm happy to answer any questions or help you troubleshoot any challenges you encounter. Happy mermaiding!