Materials: 

Size 12 - 18 months
• Main fabric - half meter
• Fabric for the straps and strip - half meter (probably will be some leftovers)
• Two buttons in the color
• Elastic waistband - 2.5 cm width
• Narrow ribbon in the color of the dress

Construction:

1. Cut 30 cm x 90 cm of the main fabric. Stitch 30 cm at the sides with right sides together. Set stitch length to the longest and sew a seam along the 90 cm side of your fabric, leaving a hanging thread from that seam.

2. Sew shoulder straps.

3. Cut two strips 6 cm x 30 cm in length. These strips will be used to make the breast band. Since we will have elastic in back dress will fit baby with chest 55 cm If you want to make it more/less, please follow the instructions below to change the size of the picture at the end.
 

Place the straps between the bands at a distance of 5 - 7 cm from each other.

4.

Here's how it looks.

5.

Fold the edges of the strips of 1.2 cm inside.

6. Sew the two short ends of the strip (right sides together).

7. Now take the main fabric, which you have prepared earlier, pull the thread from the seam left hanging, to gather the fabric. Gather so that the width of the fabric equal to the width of the strip.

8.

Align the raw end of main fabric with the raw end of the outer layer of the strip.

Sew a seam along the raw edges. Make sure that the seam falls on the fold you made in step 5.

9.

Here's how it will look after you fold it after sewing. Fold the inner layer of tape inside.

10.

Sew strips. Leave two 2.5 inch gap in the back, about 20cm from each other.

11.

Insert wide elastic through these gaps with the help of safety pins. Pull the elastic so that the total band width was approximately 7 - 8 inches less than it was. This will ensure a snug fit.

12.

Secure the elastic on both sides using a zigzag stitch. Go to the gum 3 to 4 times to ensure the strength of the seam, because the seam will be continuously energized.

13. Sew buttons on the straps directly under the band. You can do two sets of buttons for a more flexible fit. Shoulder straps can be worn straight or criss-cross.

14.

Make a small bow of narrow ribbon. Hands to sew it in the front.

Your charming dress with adjustable straps is ready!

Here are a few straps that I made last year: