Final mock-up of thong

It’s a Thong Story…

I’ve now made 2 versions of Ohhh Lulu’s Betty High-waisted Panty pattern, including this lace-overlay beauty, and I’m ready to try something new! The other day, I fished a lace thong out of my panty drawer (okay, it’s more like a bin), and it occurred to me to try modifying a thong pattern to make something similar. In this post, I’ll show you how I made the modifications, and get my pieces cut; next time, I’ll sew my thong together!

Here’s the pattern I’m starting with, Kwik-Sew 3881, which includes patterns for several basic panty styles:

Kwik-Sew 3881 panty pattern
Here’s the panty pattern I’m starting with; I’ll be modifying the thong (View D). Click the photo to view this pattern on Kwik-Sew’s website.

My idea is to replace the upper edge of the thong with wide stretch lace. Here’s the plan:

1. Trace the original pattern on to tissue paper. (Kwik-Sew’s patterns come on paper that’s quite a bit heavier than regular sewing-pattern paper, so I always trace the pieces onto tissue or pattern paper first.)

2. Draw new cutting lines on the thong front and back pattern pieces, after determining where I want to place the lace.

3. Cut new thong pieces from fabric.

4. Pin-mark mitered seams on lace (center front & center back).

5. Lay out all pieces, including elastic trim, as a mock-up, to make sure it all works!

First, I’m going to trace the original pattern, then figure out where I want the new cutting lines to be:

Modifying the front pattern
The original thong pattern is traced in purple; I’ve drawn a straight(ish) line in green where I want my lace to go, starting at the side seam (top left of pattern). The top green line is where I’ll actually cut my fabric, minus the skinny bit going out to the side.

Tip: Color-coding is a great way to keep track of your pattern modifications!


Here’s a look at my lace, laid over my newly-drawn cutting line:

Lining up the lace
Here, I’ve laid my lace trim over my modified pattern piece, just to check how it’s looking so far. I’ve also folded back the upper right corner of the lace, to get an idea of how much I’ll need to miter the center-front seam.

Tip: You could, in theory, make a deeper V with the lace in front, but I’m keeping mine relatively shallow. Here’s why: I’m not making any side seams in the lace, so the only seams will be at center front and center back. If I make the V too pronounced, the lace won’t lay smoothly as it goes around the sides to the V in center back. Make sense? The angle up from center front will have to angle back down to the center back. (At least in this case, it does; this gives me an idea, though, about maybe angling the V up in the center back…)


Note: For a look at how to size your stretch lace bands, see Size Matters: When Thongs Go Wrong.


Moving on to modifying the back of the thong pattern, I’ve drawn my new cutting line with an even shallower V than the front:

Modifying the back pattern
At the far left is the back pattern for my thong, again with green lines indicating the new cutting line. The angle here is even shallower than for the front piece. Hopefully the lace will lie smoothly.

Now I’m going to trace over the modified patterns:

Finalizing my pattern
On a separate piece of tissue paper, I’ve trace over my pattern, this time eliminating the upper parts of each piece. Notice how I’ve eliminated the skinny bits going out to the sides of the original thong pattern. (In this photo, purple indicates the cutting lines; green lines are where the lace will overlap the fabric.)

Hey, I’m finally ready to cut my fabric!

After pieces are cut
I’ve cut the front and back thong pieces, using my modified patterns, and also cut the crotch lining (using the original pattern) from a soft cotton knit. (The teal fabric is a silky bamboo/Spandex knit.)

Tip: After you’ve cut your fabric pieces, take a moment to organize your patterns! Here’s how I do it:

Organizing your patterns
On the left is my main bag for this pattern; on top of the pattern envelope, you can see a smaller bag with the traced pattern pieces. On the right, I’ve put the modified pieces in a separate bag.

Now that my pieces are cut and ready, I’m going to pin-mark the mitering of the lace pieces at center front:

Mitering lace in front
I’ve lined up the angle of the 2 layers of lace with the V-shaped top line of my front piece, then pinned along where my stitching line will be. (Note: I normally pin things with pins perpendicular to the seamline; I’m pinning them vertically here so I can test that the miter angle will work.)

Tip: As you can see in the photo above, I’ve aligned the scallops of both pieces of lace. It’s a really nice touch to have the scallops come out evenly and symmetrically. (This will be clear in the finished thong, if not before.)


Checking the front miter
Here, the pinned lace pieces have been flipped over; you’re looking at the right sides of the lace and fabric (front of thong). This is the final check to make sure the miter angle is correct.

After pinning the center back lace pieces in the same way as for the front, here’s the final check:

Checking the back miter
The back miter is pinned just as for the front; the angle is a little shallower here (and the fabric piece is a lot smaller!). You can see a bit of the continuous loop formed by the lace, now that it’s connecting the front and back thong pieces.

Now let’s do a mock-up of the thong, complete with elastic trim! I’m going to try foldover elastic for this project; it’s narrow and smooth, which will hopefully make for comfortable wearing. (In my next post, when I’ll sew this thong, I’ll show you how to apply this type of elastic. Assuming I figure it out.)

Final mock-up of thong
I’m starting to really love doing these mock-ups— this is giving me so much confidence as I move on to the actual sewing part! Now that I’m looking at this, I really like the clean finish the foldover elastic is creating, and using black trim also ties the teal fabric in with the black lace.

Okay! The pattern modifications have been made, fabric and lace cut, lace miters pinned, and trim chosen. All I have to do now is sew my thong together— that’s coming up in my next post!

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