Serial Bagmakers have designed these particular front flap trim pieces to be used specifically with thinner materials and quilting cottons. They can still be used with leather and vinyl, not a worry but have been created to only have a 3/8 (5 mm) channel so your fabric will fit in nice and tight with screw holes in the back to secure them on tightly.
Dimensions:
Overall Width: 6 3/8 (16 cm) x Depth at Center: 1 1/2 (38 mm).
Channel: 3/8 (5 mm).
Instructions:
1.First, trace the metal trim onto your paper pattern piece.
2.Add the seam allowance by measuring with a ruler. Doing it that way you will have the most perfect fit and the perfect shape.
3.They recommend adding stabilizer and interfacing in your front flap so its a little sturdy.
4.Once the flap or the piece where you will use this trim is complete and turned right side out, dry test the trim piece for fit. Now you have time to adjust if needed.
5.Topstitch if desired.
6.Slide the metal trim on again and screw it in place. Do not punch holes for the screws. Do use an awl and let the screws go through the fabric. That is where the strength is coming from.
7.You can use a clear, fabric glue like Gutermann HT2 or E6000 in the channel to secure.