This post is dedicated to some ways you can alter the upper half of the 8101 swimsuit. If you prefer adjustable straps instead of a halter-neck ties and how to make the bikini a full band and adding closures at the back.
Adding a Full Back Band to the Bikini Top
I recently made the bikini version for a client and she requested a full back band with a closure for the top. So i’ll use this as an example for how to make the changes. First lets look at creating just a full back band:
The pattern is made with a -10% negative, which means it is 90% of the total body circumference measurement.
I took her under-bust measurement 96.5cm (38″), and calculate 90% of that: 96.5 X 0.9 = 86.8cm. This means the total circumference of the bra band will need to be 86.8 cm. I measured the bra band pattern piece that I used according to her size and then added onto each end the additional amount required. If you want just a bandeau style back, you can then add your seam allowance of 1cm (3/8″) and sew the CB closed.
If you don’t want a CB seam, then you can separate the front of the bra band and create one back band. Measure about 2.5cm (1″) from the top point of the outer cup edge and draw a line down to the lower edge at a very shallow angle inwards. Then join the CB line together smoothing out join lines. Don’t forget to add seam allowance to the new side seams! If you create a separate piece for the front of the bra band, you can also underline this with power mesh to add additional strength and support under the cups.
Adding a Closure to the Full Back Band
To add in a closure you’ll need to measure the width of the closure – in my case it was a G-hook just shy of 2cm (3/4″) wide. I then narrowed the width of the centre back to that size and added seam allowance. I would recommend shortening it by taking away from the top edge of the centre back and blending to the high point at the side seam as this gives the best balance and distribution of stretch to the fabric.
Remember that the seam allowance will need to be longer to accommodate going through and sewing in the closure and a loop for it on the other side. I used 2cm (3/4″) seam allowance.
I chose to place a G-hook closure on the same side as bra hooks, as women are used to hooking at the back in the same manner. So that means if you’re looking at the bra band flat, right side up, the closure is on the left and the loop is on the right.
You could also add a G-hook or other swimsuit closure to Version 2 of the swimsuit, if you want the one-piece with a low cut back, but like having some support around the back of the chest.
Adjustable ‘straight’ straps
If you’re not too keen on having a halter-neck here are the steps you can take to make them into adjustable straps that are more akin to a standard bra. You’ll want to do these steps before sewing the straps onto the cups.
You’ll need: two sets of bra rings and sliders, wide enough to accommodate the width of the two neck straps, something that’s at a minimum around 1.5 cm (5/8″) size would work.
For each cup have one rouleaux strap 20″ long. Slide a ring through the strap, then sew the two raw ends of this rouleaux strap to the cup as per the instructions.
For the adjustable strap at the back you’ll need two straps, around 33-38cm (13-15″) long. They’re final width will be as much as the ring and sliders allows.  For this example that width is 1.5cm (5/8″). Cut two rectangles 33cm X (1.5cm + seam allowance).
Fold the seam allowance inwards and topstitch it down with a zig-zag.
Then feed one end through ring attached to the front rouleaux straps (1), then through the middle of the slider, fold the end down and stitch (2). 
Take the other end and feed it through the ring (3) – which has the front straps. Then feed that end through the slider (4).
Sew this remaining raw end to the top back edge of the swimsuit.
You’ll want to check you’re preferred placement on the back, but a good rule of thumb is 8-9cm (3 1/2 – 4″) from the CB. Then you’re done!