Cut two pieces of cotton fabric to measure 12 inches by 5 inches. Align the felt piece with the bottom edge of one of the fabric pieces. Fold the ribbon evenly and place 1 inch of the loop part of the ribbon at the top edge of the felt. The ribbon strings should lay on the felt for now.
Align and lay the second fabric piece on top of the other fabric piece, the ribbon and the felt. Make sure that the design on the fabric is not showing when you lay it on top of the other materials. Also, make sure that the little loop of the ribbon is still poking out of the fabric.
Stitch around the edges of the fabrics but leave a small opening. This will allow you to pull the fabric case inside out. When you're done, the ribbon and the felt should be in place. Turn the case inside out by pulling the inside of the fabric through the hole that was left open. Flatten the case out with your hands.
Fold over the edges of the opening you left unstitched to match the rest of the fabric case. Baste the area you've just folded. To baste, set your sewing machine on the longest stitch and sew. Then sew another border around the edge of the entire fabric case making sure this time that the part you just basted is included in the stitch. Sew one more stitch around the border of the case. This stitch should be 1/4 inch away from the first stitch you just created.
Create little pouches in the felt for your crayons. The number of slots depends on the amount of crayons you want to hold. Mark the width for each column using chalk for even stitching. Sew a continuous stitch to create pouches. Start at the top of the felt and stitch downward, move to the right about 1 inch and then stitch upward. Move over to the right about 1/4 inch to start the next pouch and repeat the pattern until you create the last pouch. This will create a "U" shape for each pouch around the felt.