Here is the cutting layout, although it doesn’t include the second apron piece laid out. These measurements are for an apron that fit my Owen, who wears a 2T. The same concept embiggened would fit an older child, or even yourself. Just measure yourself where an apron would be, and remember to halve the measurements for cutting on the fold, and to add enough for a 1/2” seam allowance.
Once your pieces are cut, assemble the apron strings. I usually assemble strings and straps thiswise: fold them in half lengthwise and press, then unfold. Fold from the edge to the center fold line lengthwise for top and bottom. Press. Then fold in half, enclosing the raw edges, and sew along the open side. Turn one short edge under twice and stitch it down.
With the right side of one of the unfolded apron pieces facing up, lay the apron strings in the appropriate places, raw edges matching and strings toward the center. Pin them in place as shown below. Lay the other apron piece on top, right sides facing. Starting about 3” from the center bottom, stitch all the way around the edge, using a 1/2” seam, and going over the straps. Stop a few inches from where you started to leave room to turn (be sure to backstitch).
Be sure to clip the seam allowance nearly to the stitching line on the curves, to make them lie flat, and trim corners at a 45-degree angle to eliminate bulk.
Turn it inside out. Press.
Suckers will hand-slipstitch the opening closed; lazy people like me will edgestitch the whole thing. Then voila! Apron!