Here is an easy way to make a perfectly fitting bandeau top from an old tank top. I used the bottom half of the tank top I used for the crop top DIY so you can easily get two tops from one tank top!
Supplies you will need for this project:
-The bottom half of a tank top
-Elastic that is 3/8″ wide or less
-Fabric Marker or Chalk
Step 1: Figure out how long you would like your bandeau to be. If you would like it to be closer to a bandeau bra, measure on your body what the shortest possible length would be and then add two times the width of your elastic. Draw a line and then cut there one layer at a time.
Step 2: Take your elastic and wrap it around the top of your bust. When you feel like it is the tightness that you want, pinch the spot where you would like to cut and cut it with your fabric scissors. Measure the length of your elastic and set aside the measurement for later.
Step 3: Bring together both ends of the elastic you just cut, ensuring that the elastic has not twisted, and sew across so they are firmly attached. Set this aside.
Step 4: Use the measurement you wrote down earlier and cut another piece of elastic at that length. Take one end of this elastic and attach a safety pin.
Step 5: Take your seam ripper and open up the side seam inside the hem allowance just enough for the elastic to fit inside the hem allowance that is already there. Push the elastic through the casing and full the fabric over top of the elastic as you go. Once the elastic has been fully threaded through the casing, remove the safety pin and sew both ends of the elastic together.
Step 6: Close the casing by whip stitching the spot where you seam ripped open with a thread and needle.
Step 7: Take the elastic that you set aside and mark 4 times equally around the elastic the same way as the DIY crop top tutorial. Pin one marking to the side seam on the inside of the raw edge of the bandeau. Pin the exact opposite marking to the other side seam. Mark the centre front and centre back of the bandeau at the raw edge. Pin the other two markings on the elastic to the centre front and centre back markings.
Step 8: Sew along the raw edge with a zig zag ztitch, stretching the elastic to match the raw edge as you go.
Step 9: Fold over the raw edge towards the inside of the bandeau. Sew with a wider zigzag stitch with the fold touching the 1/4″ mark on the sewing machine. Stretch as you go. This will be the top of the bandeau.
Step 10: Put the bandeau on yourself or a dress form and pinch the top of the centre front about an inch and secure with a safety pin.
Step 11: Take your needle and thread and hand stitch up the centre of the gathered portion. Continue to go through the gathers several times, pulling it tight, until you get the look that you desire. Be sure to knot on the inside of the garment and you’re done!