3350 Sewalong // Part 1 // FABRIC & SUPPLIES

 Starting next week, we soon show you how to make a stunning one-piece swimsuit from A to Z. Instead of doing a sew along that would last a few weeks, we want to post everything within a few days so you can finish this project quickly or take it slowly if you can only work on it a little bit every day.  

If you get stuck, post your question in the comments section and we will gladly help you.  

Jalie 3350 Swimsuit - A (sweetheart) front with A (open) back


While we are getting ready for photos and sewing, I thought it would be a good idea to start with some useful information and inspiration photos so you can gather your supplies before we start posting tutorial photos next week.



We will show you in detail how to make a 3350 one-piece swimsuit.



This pattern includes 27 sizes (yes, all in one enveloppe!) and we worked very hard at adjusting the style (leg openings, cup coverage) so it fits beautifully, from toddlers to plus sizes.




A front: sweetheart with contrast band (EASIEST)


A back: open back with G-hook closure (EASY, REQUIRES A G-HOOK, A FEW EXTRA STEPS)

B back: closed front (with optional tummy-control front lining) (QUICKEST, BUT CAN BE A BIT HOT IN THE SUN)


Jalie 3350 Swimsuit - B (twist) front with A (open) back

Jalie 3350 Swimsuit -  B (twist) front with A (open) back



Extra variation: We will show you how to alter the lower front pattern piece for a gathered front.




Main fabric

You will need a good quality lycra with nice stretch and recovery both in the length and in the width. When shopping for your swimwear fabrics, look for nylon/spandex or nylon/lycra. If you plan on making a tummy-control version (full back, powernet lining), you want to avoid the beautiful poly/spandex prints for the bottom part of your swimsuit as they are thinner / have less body and don't look as beautiful when stretched out.


You can find great swimwear fabrics online:


You can find swimwear lining at all three stores listed above. We often see beige lining, but we prefer going with black or white, whatever compliments the fabric best. For a tummy-control swimsuit, you can use PowerNet (a mesh with limited stretch) for the lower front. You will still need regular lining for the bust. 

Please refer to the back of the pattern for yardage. If you would like to gathers at lower front, please add 1/3 yard (30 cm) to the lower front fabric yardage.  



With the sweetheart, you can use one, two or three different fabrics. Your fabric choice will help you enhance your body's best assets. It looks great in solids, stripes, florals... You can also use the straps if you want to add a little pop of color too.

  • To enhance, use a lighter or bright color or go with an eye-catching print.
  • To minimize, go with a darker color for the bottom piece or more subtle print.
  • To emphasize curves, pick a print that creates a cut-out or princess seam effect.




The twist front looks best in a solid or print that will make the twist detail stand out. With some florals, the twist becomes less visible. You can use the same fabric all over, or go with contrast twist front or straps. There is no contrast band on this one.



In addition to your fabric and lining, you will need:

  • 1 cm (3/8") Elastic 
    • Knit elastic: That is what we have always used on swimsuits because it is very easy to sew and has great stretch and recovery without being too stiff. It always had a great lifespan too. It is also easy to find in most fabric stores. Do not use braided or woven elastic. We explain why in our How to Sew Elastics video.
    • Rubber: Our favorite is by far FILPAR rubber elastic
    • Requirements (error in elastic yardage on the back of the pattern) please use these quantities:
      • Young children (sizes F-K): 3 m (3 1/4 yd)
      • Teens (sizes L-O): 3,5 m (3 7/8 yd)
      • Women (bust 31" to 36"): 4 m (3 1/4 yd)
      • Women (bust 37" to 50"): 5 m (5 1/2 yd)
  • Rings and sliders
    • Only if you want adjustable straps
    • You can find them at Sew Sassy and Bra-Makers
    • If you plan to spend more time in the sun than in the water, you can use bra strapping for your swimsuit straps. They will save you some time and will look just as good (but do not resist as well to chlorine or salt water)! Sew Sassy sells strap kits that includes the straps, rings and sliders. 
  • G Hook
    • For open back only (great to minimize tanning lines!)
    • Available at Bra-Makers Supply and Sew Sassy
    • If you cannot find one, don't worry. You can still make the open-back style, but the top section will simply sewn at center back.
  • Cups (optional)
    • You can steal cups from another swimsuit / bikini you no longer wear or find some at lingerie stores or online


We have been using Schmetz Stretch needles on all our projects since 1983, on both our regular machine and serger.


You can make the 3350 swimsuit with a regular sewing machine. If you have a serger, you can use it for construction seams and for a clean finish. In the assembly post, we will show how to get great results with both. Meanwhile, you can take a look at our sewing technique for stretch fabrics using a regular sewing machine on YouTube:






You will need the usual:

  • tape measure
  • pins
  • good scissors (I strongly recommend you put this pair of Kai scissors on your Christmas or birthday list!)
  • fabric marker / tailor's chalk
  • thread (we use 100% polyester thread on both our regular machine and serger)

  • tape (for PDF pattern assembly)

  • tracing paper + pencil/pen or plastic sheeting + Sharpie (my personal favorite)

I think that will be enough for today :) Gather your fabric, order your pattern through our website or your favorite Jalie retailer and free up some time in your schedule next week for your fabulous swimsuit project!

The next post about sizing and pattern alteration. 

← 3136 Skating Dress // Video Tutorial 3350 Sewalong // Part 2 // Pattern & Sizing →