I have twin daughters who are 20 years old. They do not dress alike though, neither in the "real" world or when we dress up in medieval clothes. Valeria, show' theone who is most active in the SCA goes for 16th century and Vendela likes 14th century fitted dresses from the second half of the 14th century.
I actually made this dress in 2010, when she was 16. She hasn't changed much in size. it is made from a dark navy thin wool tabby and lined with linen. While fur, silk or wool were more common materials for lining you also find linen as lining in the 14th century. For instance there are two (male) cotehardies mentioned in Norwegian wills lined with linen or cotton.
The buttons are modern metal buttons, but pretty. And I've seen worse.
I bought lots of them c. ten years ago, both in silver and gold and it turned out that Vendela liked the gold ones too, so I used them on her new dress that was finished in the beginning of April 2015.
The material in this one is a viscose/cotton damask that I bought from a friend some years ago.
When you fitted gowns in patterned fabrics in medieval images they are usually not open in the frotn, to show off the pattern. I chose to use side lacing on this gown, since it is documented for instance in this manuscript, the Golden Haggadah from the 14th century.
After we got in I made her try on an old sideless surcoat that really needs ironing, I haven't used it this millenium ;)