A large rectangle of natural fabric, such as linen,wool, or cotton, worn as a tunic and belted with twine makes for an easy Medieval costume. Wear leggings and an undershirt underneath for modesty, and leather sandals for added authenticity. Women wear hair loose or braided while a straw hat is the perfect touch for men.
For a more elaborate Medieval costume, consider a knight in shining armor or a fair lady of the court. An easy way to make authentic-looking chainmail for the knight is to purchase a large-looped sweater from a thrift shop. Use a can of metallic silver spray paint to paint the sweater, and let it air dry for a few days. Cut a tunic out of heavy fabric and, using fabric glue, attach an insignia of choice on the front. Make a sword and shield out of heavy cardboard, pair the tunic and chain mail with leggings and leather boots, and the Medieval knight is ready for battle.
For an elegant Medieval lady-in-waiting, search second-hand stores for a long dress in a rich color such as royal blue or emerald green. Use a hot glue gun to add embellishments such as metallic gold string around the hems, edges of the sleeves and waist. Add heavy costume jewelry such as rings, bracelets and a necklace to complete the look.