How to Sew Shelf Bras. A shelf bra is a good addition to a shirt when you are concerned about bra straps showing. You can add a shelf bra to an existing tank or tee with minimal sewing skills. Another option is to adjust the pattern of a shirt you're sewing to include one.
Use the front and back of the shirt to trace the neck, side seams and center front to create a pattern for your shelf bra. Add 2 to 4 inches to your template. If you are adding a shelf bra to a shirt you are sewing, extend the front and back pieces. The measurement of 2 to 4 inches depends on the size of your bust.
Measure the top of your breast from where the top of the shirt would be to the bra band. Transfer the measurement to your shelf bra template from the top point of your shirt or pattern.
Match the side seam on the front piece of the bra pattern with the back piece and draw a line straight across.
Pin the front and back pieces together and hold the template against your body to make sure the measurements are accurate. The shelf bra should fit snugly against your bust.
Cut your elastic after measuring to fit around your ribcage just below your bust. Sew it to the band of the shelf bra.
Sew the top and side seams of the shelf bra together. Insert the bra into your existing shirt and stitch it together, or add it to the shirt pattern and finish sewing the top.