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A stretchy knit or jersey fabric works well for making a baby car seat cover. This type of fabric will mold itself around the outside of the car seat for a snug fit while still allowing air to flow through the fabric. Jersey fabric and other types of stretch knit fabric will not fray around the edges and do not require hemming. Make sure to pre-wash the fabric to ensure that it won't shrink after you make the car seat cover. Take the 2 shortest ends of the fabric and line them up so that the fabric is folded in half. Smooth out the fabric to ensure that there are no bumps. Fold the fabric the same way that it was folded when it came off of the bolt. Line up your ruler with the folded edge so that it is flush with the top of the fabric. Then, insert a pin at the 6.5in (17cm) mark. Push the pin through both layers of fabric. Use a clear ruler with angle lines across it to identify where to cut your fabric. You can find this type of ruler at a craft supply store. Follow the 45 degree angle line from the first pin down to the bottom of the ruler. Then, insert a pin at the bottom of the 45 degree angle line. Make sure the pin goes through both layers of fabric. Then, measure from the pin with the measuring tape. Angle the measuring tape so that it is going across the second pin. Continue measuring at a 45 degree angle and place a third pin at the point 13in (33cm) from the top edge. You may also use a ruler to locate this point if you have a ruler that is long enough. Align the bottom corner of the clear ruler with the last pin you placed. Then, flip the ruler over going towards the bottom edge of the fabric to reverse the direction of the angle lines. Measure 13in (33cm) down from the last pin you placed. Use the measuring tape and clear ruler to position the measuring tape at a 45 degree angle from the pin going towards the bottom of the fabric. Place a pin at the 13in (33cm) mark. Remember to measure in the opposite direction. This angle should mirror the first one. Use a sharp pair of scissors to cut the fabric going around the outside of the pins. Cut from pin to pin to get the required shape. The finished piece will be a hexagon, which is a 6-sided polygon. Repeat to make a second hexagon in the same dimensions as the first. Place the first piece right side up on a flat work surface, such as a table or clean hard floor. Then, place the other piece on top of this piece with the right side facing down. Make sure that the edges of the pieces are even. Locate the top edges of the hexagons and place 3 evenly spaced pins along each of the angled edges. Insert the pins so that they go all the way through both pieces of fabric. Smooth out the fabric pieces to ensure that there are no bumps before you pin them. Position the pins so that they are perpendicular to the edges. This will make it easier to remove them as you sew. Set your sewing machine to the zigzag stitch setting and then place the end of the first angled edge under the presser foot. Lower the presser foot and apply gentle pressure to begin sewing along the edge. Sew from 1 end of the angled edge to the other. Then, stop the machine and cut the thread. Repeat for the other angled edge. If possible, install a ballpoint or stretch needle before sewing your car seat cover. Otherwise, a universal needle will be fine. Make sure to remove the pins as you sew. Do not sew over them or you may damage your sewing machine!
Purchase a yard of stretchy, breathable fabric. Fold the fabric in half width-wise. Insert a pin 6.5in (17cm) from the edge of the fold. Measure 13in (33cm) down at a 45 degree angle from the first pin. Use the ruler to identify and mark another 45 degree angle. Cut along the pin marks to create a hexagon and then make a second hexagon. Pin the 2 pieces with the right (print) sides together. Sew a zigzag stitch 0.5in (1.3cm) from the angled edges.