Place red denim rectangle right side down on an ironing surface. Fold over one short edge 1⁄2"; press. The iron is hot; keep your hands away from the heat. Fold over the same short edge again 1⁄2"; press and pin. Repeat with remaining short edge of red denim rectangle and one long edge (photo 1).
TIP: It helps if a pair of extra hands holds the fabric straight while you press.
Sew along the three folded edges to hem and make apron body (photo 2).
TIP: Do not sew over pins. Stop stitching and remove each pin right before the needle gets to it.
Fold and press purple denim 6×8" rectangle 1⁄2" from one 6" edge. Topstitch folded edge using a straight stitch. Fold over remaining edges 1⁄2"; press and pin (photo 3).
Place apron body right side up on a flat surface, with unhemmed edge at the top. With a fabric marking pencil, make a mark 6" from left-hand edge and 4" from bottom. Place bottom left-hand corner of the Step 3 purple rectangle at the intersection of these marks, with topstitched edge of rectangle at top (photo 4).
Topstitch 1⁄4" from three folded edges of purple rectangle to make pocket (photo 5).
Place apron body right side up on a flat surface, with the unhemmed edge at the top. With a marking pencil, mark 2" and 4" from one side edge. Repeat to mark opposite side edge in the same manner (photo 6).
Pinch a fold at top of apron body, starting at one 2" mark and matching it with the nearest 4" mark, to make a pleat. Pin fold. Repeat with remaining 2" and 4" marks to make a pleat on opposite side (photo 7).
Sew a purple denim 3×21" strip (tie) to each end of purple denim 3×25" strip (waistband) to make a waistband tie. Press seams open. With wrong side inside, fold under 1⁄2" along all edges of waistband tie; press (photo 8).
Find center of apron body and waistband tie by folding each in half widthwise; finger-press. Unfold long pressed edges of waistband tie. With right sides together and raw edges aligned, center and pin a long raw edge of waistband tie to apron body (photo 9).
Starting at one side, join pieces along top edge of apron body (photo 10).
Press sewn section of waistband tie away from apron body. Refold long edges that were pressed under in Step 8. Fold waistband tie in half lengthwise, bringing long folded edge to back of apron body; pin along length of waistband tie (photo 11).
Topstitch around all edges of waistband tie to complete apron (photo 12).