Here are directions on how to make a simple medival dress. They aren't great. So if you don't sew, find a friend who does, and get them to help you.

home made medival dress

You can use all the same fabric, or make the sides a different color or make the sides and sleeves a different color. I suggest using linen. Linen is so wonderful. it has a nice weight, good flow, and its soft and comfortable. Cotton also works. One typically sees these dresses in solid colors. but if you find a nice print, that could also be cool. If you are feeling ambitious, get some trim to put around the hem, sleeves and/or neck to dress it up. :)

Another note: don't cut your sleeve too small! remember, its better to make your dress too big and then take it in. If you cut it too small its a pain to add extra fabric.

Other options include these lovely medival dress patterns by McCalls. 4490 (the underdress) and 4491 (the overdress)