In this example, I am using a premium prefold and making a medium sized fitted diaper with the rounded corners option.
Step 1: Trace pattern onto prefold ensuring the pattern is centered over the middle or thickest part of the prefold. Mark elastic and snap points. I trace onto the side that is one continuous piece vs. the size that has a fold in it.
Step 2: Cut away extra material on the sides, leaving some fabric between your cut line and your tracing line for serging.
Step 3: Cut off top and bottom.
Step 4: Cut open ends of wings where pattern ran off the fabric.
Step 5: Use one of the side remnants to add to the wing length. Cut remnant in half lengthwise and width-wise so you now have four pieces that are two layers each.
Step 6: Separate layers on the wings and sew one piece of side remnant (two layers) to two layers of wing, right sides together. Turn sewn piece over and top stitch over seam. Repeat on remaining two layers of same wing. Repeat on other wing.
Step 7: Place pattern back onto fabric and finish tracing the wings.
Step 8: Remove stitches as shown in red on photo below to allow room for blind elastic. I found it easiest to reach in between the fabric layers and cut the stitches with my seam ripper.
Step 9: Open up layers and sew elastic in between the layers about 3/8″ to 1/2″ in from tracing line. When separating layers, be careful that your elastic is going in between fabric – on the other side of the prefold, the flap is open once the stitches are removed. I usually sew my elastic so there are 3 layers of fabric on top (where I’m sewing and what will be the outside of the diaper) and 5 layers on the inside by baby. Start with the legs, then do the back elastic. Tack elastic down above elastic marking point. Place your hands in between the layers and pull a couple of inches, maintaining an approximate distance of 3/8″ to 1/2″ from the tracing line. You will be sewing between all layers of fabric. Feel through the fabric to your elastic and sew a couple of inches at a time with a wide 3-step zig-zag stitch until you are at the end elastic point, then backtack. Tip (or warning): One side of the prefold will have more layers in the leg elastic area than the other so be sure to stretch the elastic tighter on the side with more layers to ensure even gathering or vice versa…stretch less on the side with less layers.
Step 10: Straight stitch the areas where you removed stitches in step 8 but do not go over your elastic. Be sure to backtack over the ends of the stitches that you took out to secure any loose threads.
Step 11 (Optional): Add snaps and any decorative elements between layers for hidden snaps.
Step 12: Starting on one side where the fabric is gathered, serge around all edges. I generally serge on the trace line but I do serge off the seam allowance on the back wings to ensure a proper fit around the waist.