You will use an insole in each shoe you make. Match the fabric to the lining of the shoe. If you’re planning to make a bunch it would be more efficient to cut a lot of cardstock pieces all at once.
Cut one pair of soles from fusible interfacing. Make sure you’re cutting a pair so there’s a fusible side for each foot.
Cut one pair of soles from cardstock, carefully trace all alignment marks and a line 1/2 inch from the edge onto each. Using a lightbox or window can make this easier.
Fuse the interfaced pieces onto the lining fabric, allowing space around the edges.
Cut around the interfacing leaving about a 1/4 inch margin.
Adhere the interfaced fabric to the cardstock on the back (unmarked) side of the cardstock using spray adhesive or E-6000. If you use spray adhesive spray it onto the cardstock, not the fabric.
Clip the fabric around curved areas.
Fold the fabric over the edge and glue down using E-6000. Ensure that the reverse has a nice edge as this will be the inside bottom of the shoe, and that they fabric is securely glued in place. It should be trimmed down so that enough of your marks are exposed that you can easily align the upper.