Cut a tabard shape from a thick, cotton sheet with craft scissors. For a regular-build adult, cut a rectangle of cotton about 24-by-36 inches wide. Lay the rectangle flat on a work surface.
Measure two points at the top of the sheet. The first is 6 inches in from the left-hand side; the second is 2 inches closer to the middle from that, which is 8 inches from the left side. Mark them with a pencil. Mark a new point between the first two about 4 inches in from the top of the sheet. Use a ruler and pencil to draw a triangle between the three points. Place a side plate on the sheet so it only intersects the bottom of the triangle, and is offset from the triangle toward the middle of the sheet. Draw a circle around the plate. As a guide, the middle of the circle will be about 10 inches in from the left of the sheet and 7 inches in from the top. The circle makes an arm-hole for the vest carrier.
Measure and mark a new triangle at the corresponding points from the right-hand side of the sheet at the top. Use the side plate to draw a circle that intersects the tip of the triangle, offset to the middle. You now have a shape that makes a mirror image of the shape on the left.
Cut the triangle and circle shapes out of the rectangle, starting from the top and working down around the circle and back to the top. Do this for both armholes. Overlay the two edges of the sheet that had formed two sides of the triangle on the left side on one another. Pin them in place. This closes the armhole circle. Do the same for the right armhole. Sew the two hemmed edges together for both armholes. This creates two seams, which run from the back to the front over the shoulders.
Sew a roll of fabric hook fasteners on the left edge of the vest carrier from the bottom corner to about halfway up. Sew the corresponding loop fasteners on the right edge from the bottom corner to the midpoint. Try the vest on and use the hook-and-loop fasteners to connect the vest down your middle. The tabard-shaped vest should hang loosely around your body to accommodate the storage pockets and contents of your vest carrier.
Measure two rectangles from the remainder of your cotton sheet. They should both be 10-by-8 inches. To form pockets, lay them out side by side with the long sides facing you. From the four corners closest to you, cut off a right-angled triangle. Each triangle must remove 1/2 inch of material from the bottom and the side of the rectangles. Fold back the material at the sides and bottom of both pieces of cotton to make three hems on each.
Place one of the two new pieces of cotton on the vest, in the middle near the bottom. Pin the three hems in place and sew the pocket in place along the three hems. Turn the vest over and pin the second piece of material in place at the hems to form a matching inside pocket. Sew this in place from the inside.
Make six smaller pockets from your remaining cotton sheet. Cut squares of 6-by-6 inches. Remove two corners from each by cutting off triangles. Fold back 1/2 inch of the material to form three hems, one at the bottom and two at the sides. Pin two pockets in place, one above the other, on the left side of the outside of your vest carrier. Pin another two pockets to the corresponding positions on the right-hand side. Sew all four of them in place. Turn the vest over and pin the hems of the final two pockets to the inside, one on the left and the other on the right. Sew the final two pockets to the tabard.
