Introduction: DIY Bikini From Scratch

About: Hello! My name is Sam, and I am a college student majoring in fashion design who loves to make jewelry and other DIY's! Please contact me if you need any help with my tutorials, or if you are interested in pu…

I was so excited to put my sewing skills to use this summer, and what better option than a custom bikini! I haven't gotten a chance to show it off yet, but I am planning to this weekend. This is a pretty simple design and concept, but I would suggest some sewing experience if you want to attempt this DIY. Good luck and feel free to contact me with any questions!

Step 1: Materials

This instructable requires a basic knowledge of sewing and patternmaking. Aside from that, no fancy tools are needed!


1 Yard of spandex swimsuit material (found at joann fabrics)

Black Thread

Sewing Machine


Rulers (straight edge and a curve if you have one)

Tissue paper

Bra cups (found at joann fabrics)

Bikini that fits well.


You also need to give yourself about 3 hours. I split up my time a lot, and I still completed this relatively quickly!!!

Step 2: Creating the Bikini Bottom Pattern

This step is crucial to the fit of your bikini. You cannot simply trace the pattern of your bikini bottom!

1. Take the bikini bottom and lay it flat on your tissue paper.

2. Use the pen to create dots about 3/4 of an inch apart using your bikini bottom as a template.

3. Take a look at the design you created. Connect the dots. Do you like the lines? Do they make sense?

4. Flip the bikini bottom over. Now do the same for the other side. I luckily had a bikini that tied at the sides so this was easy for me to trace.

5. Look at your design, make sure that the seams that will be sewn together match up realistically. If they do congrats!

6. Now you need to use a ruler (or seam gauge if you have one) to mark 1/2 inch away from the traced design you created. Connect the dots of this line too. This is your seam allowance. If you want more in case of mistakes, just mark the dots farther away from the tracing.

7. Now cut the tissue paper shapes out along the seam allowance lines. You just patterned a bikini bottom!!! Easy right?

8. If you want to, you only need to trace half of the bottom. You can do this because you will cut the bikini out on the fold. This will help ensure that your design is symmetrical. Make sure you DONT add a seam allowance to the fold. Look at pictures for a better understanding.

Step 3: Creating the Bikini Top Pattern

I decided to stick with a pretty simple black bikini top for this tutorial. This didn't require the old bikini top to use as a stencil because I had the bust cups.

1. Create the basic shape of your bikini top. I wanted it to be more complex than a simple triangle so I added a little curve and shape.

2. Fold the tissue paper in a dart shape to design the curve of the top. Make sure that this mimics the curve of the bra cups. This is important, but you don't have to be an absolute perfectionist about it because you are using a stretchy material.

3. Now do the same process you did for the bikini bottom of tracing the shape of the bikini then adding a 1/2 inch seam allowance all around. The useful thing about making a bikini is that it is symmetrical, so you only need to create one pattern for the bust.

4. Make sure to mark the dart shape that you created with pencil at the two folds and the top point. Then draw out the line. This is very important for making a uniform dart along the whole top.

Step 4: Cutting Out Your Pattern in Fabric

Okay. Now the important part. The cutting.

1. Lay out your fabric folded in half with the selvedge edge perpendicular to you. (The selvedge is the edge of the fabric with a finished edge)

2. Lay your patterns on the fabric, with the fold of the fabric aligning with the fold on the bikini bottom. The bikini top should be straight on the "grain" of the fabric (you can google this!). Now pin the patterns to the fabric well. You don't need pins every few centimeters, but I would suggest at each corner and a few in the middle. Using a good pair of scissors, cut out 1 of each of the bottom pieces, and two sets of the top pieces. (Since the fabric is folded in half you need to unpin the one set after you cut it out and do the same thing again.)

3. Keep track of the right and wrong sides of the fabric. Believe me, I've messed this up before and it sucks.

Step 5: Sewing the Bikini Bottom

Wow, we're just speeding through this right?!

Okay, now is the fun part! We get to sew!

Note: I feel like there is some elastic thread I should have sewed with, because when I stretch the fabric, I get worried about the seams popping.

1. Pin the front and back together, right sides in.

2. Sew the side and bottom seams with the half inch seam allowance.

3. Try it on and check for fit, note that it still has the seam allowances, so it should be 1/2 inch large.

4. Now, this is what I've been taught is a faux rolled hem. I folded the seam over, wrong side out still, by a tiny bit (guesstimated, but around 1/4 in) and sewed a straight line. This left the raw edge exposed on the inside of the bikini. I then rolled this seam over again, hiding any raw edges and sewed another straight line. I did this to all the edges of the bikini bottom and then tried it on again. Perfect fit!

5. Now this part is optional and I may do it later: Embellish, be creative! Add lace or beads or rhinestones or studs! Just make sure that they can handle water well. It IS a swimsuit after all.

Step 6: Sewing the Bikini Top

This step is definitely the most difficult. I had some struggles sewing the fabric, (it liked to roll up in the machine foot) and I had some fit struggles (I'll go into those later)

1. Sew all your darts. My tried and true method of pinning darts for sewing is to use one pin to pin through the edges of the dart "legs" and then put a pin through the top of the dart. Then I carefully remove the tissue paper and pin the dart together. This is really best explained by images, check them out!

2. The reason we have 4 bust pieces is because we need to create a "pocket" to insert the cups into. After sewing the darts, I pinned two pieces together, right sides in. One set for each side. PLEASE MAKE SURE YOU ARE SEWING THE CORRECT SIDES OF THE FABRIC NOW!! Also, make sure that you have one of each side of the bust. It would be pretty awkward to make a bikini with two left boobs.

3. Now, before you sew, you need to make a spandex piping for the halter neck. I cut a long strip of the spandex 1 1/2 inches wide. I then folded and sewed the strip right sides together so that I had a narrow seam about 1/4 inches from the folded edge. I put a safety pin on one side, and fed it through to the other side, turning the seam inside out so that the raw edge was inside the seam. Now you have piping! I measured my neck to the top of the bikini on myself and cut that leaving an extra inch. I then inserted this into my "pocket", with a 1/2 seam allowance on each side. Please please look at pictures, I promise they're super helpful. I took a lot.

TIP: You can understitch the lining of the top so you don't get any weird bunching in the suit when you're wearing it. To do this you simply sew the seam allowance to the lining. Look at the pictures and google it for more detailed instructions!

4. You have the basic shape of your bikini top now. However, you may find that the cups do not fit well into your pockets. In that case, you simply trim them to fit well. They are really easy to cut. I turned the one that was cut well inside out and used it as a pattern for cutting the other. See in picture.

5. Now you need to cut another SUPER long strip for the underbust strap. This should be plenty long enough to fit around you under the bust and have extra length to tie off. I made this two inches wide by however long my fabric was. I then folded the edges in, and that piece in half. You're basically folding it into quarters lengthwise. Look up bias binding for a better reference, just don't cut the fabric on the bias. I pinned that piece to the cups (I inserted the cups into the pockets at this point). This is really difficult to pin together, so take your time and be careful. Also, don't be hesitant to use a ton of pins.

6. Sew all of this together, and then fold the edges of the underbust strap ends and sew them down. YOU HAVE A BIKINI TOP!!! It looks so much simpler in writing, but don't be daunted by the task. You really can do it. I then added another strap around the center of the chest because I did not like how it was gaping.

7. Again, add embellishments as you wish. You now have a stylish, custom bikini to show off to your friends, for under $10! I'll probably add more details as I find time to. Please post pictures of your work! I would love to see what everyone has made!

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