Step 1: Gather materials
1 x keyfob hardware [these are available for sale on ebay and other places online] If you can't get one of these, see this instructable on how to make one using a D ring.
1 x medium weight cotton fabric, at least 27cm x 7cm
1 x fusible interfacing 27cm x 7cm
1 x fusible interfacing 27 cm x 3cm
1 x Cotton tape approx 3cm x 27cm [this is not adhesive, but a woven length of cotton available from a fabric store]
Polyester machine thread
Blunt nosed pliers
Step 2: Iron
b. Place large piece of fusible interfacing shiny side down on wrong side of fabric.
c. Check placement and iron interfacing onto fabric. It is best to cover the whole thing with a sheet of brown paper or baking paper to avoid melting the interfacing.
Step 3: Cut and mark
b. Measure exactly halfway on the 7cm edges [3.5cm] and mark with an erasable marker or tailor's chalk.
c. Measure exactly halfway on the 2nd piece of interfacing [3cm x 27cm], on the the short end as above. Mid point will be 1.5cm
Step 4: Iron some more
b. Iron interfacing to fused piece, in the same manner as before.
c. Fold long side edges over, using the middle interfacing as a guide. The edges should overlap in the middle and the whole width should now match the width of the hardware. See attached pictures for further clarification.
d. Iron creases.
Step 5: Place tape and sew
b. Using a 3mm stitch and topstitch or jeans needle, sew close to the edge of the tape, attaching it to the fabric and hiding the raw edges on the long side. Stitch very carefully as the stitches will be visible on the outside of the wristlet.
Step 6: Almost there.
b. Match raw edges, right side up. This means the cotton tape side is inside the loop.
c. Sew raw edges together, approx. 5mm from edge. This keeps it all together when attaching the hardware.
Step 7: Fasten hardware
a. Find a scrap of fabric to protect the hardware when closing it.
b. Line up the fabric loop in the open hardware, making sure it doesn't hang out over the sides.
c. Cover the hardware with the spare fabric and using a pair of blunt nose pliers, begin to squeeze the hardware closed.
d. Before it is fully closed, check the placement of the loop again, because if it has slipped you'll want to reposition.
e. Fully close the hardware with the pliers, squeezing as tight as you can.
Step 8: Finishing Touches
If you want to get really into it, you can embellish the fabric with ribbon, beads, embroidery or whatever takes your fancy. Just remember that it will probably get banged around a bit in bags and the like so make sure whatever you do is hard wearing.