The construction is based solely on rectangles and triangles. The torso is made from two rectangular pieces with a width that is half of a tightly taken waist measurement (+ seam allowances of course). Width over the bust and hips are then added with triangular gores. It is laced at the sides, which can be seen in quite a lot of period art and also, if you remember to knot the laces, which I didn't, produces the characteristic "smile" under the belly, where the lacing makes the sides sit higher on the hips than the front.
Under the bliaut I'm wearing a linen chainse in pale pink linen.
Coloured linen was probably fairly uncommon in the Middle Ages because linen is hard to dye and it's even harder to get it to keep the colour. In most pictures you see only white linen and the preserved examples of dyed linen that I know of are later than the 12th century. Since I wanted a coloured chainse, which in period sources is made from linen, I choose a pale colour which I feel is more likely to have been produced. This type of pink is fairly easily produced with orchil, but I don't know if you can dye linen with orchil. The image below is from the Missal of Henry of Chichester, from c. 1250, which is at least 60 years later than my dress, but I still use it as justification for a pink chainse, knowing that the Madonna might wear different clothes than other women (this is more pronounced in the later Middle Ages however).
If you compare the underdress of the virgin with the kneeling monk's (probably Henry) white clothing you see that her dress is definitely pink.
The chainse is made from a straight piece, 62 cm wide and 3 metres long and two gores, sleeves and gussets for the sleeves. In the long piece a vertical slit is made for the neck, just like on the Kragelund tunic. The gores which reach the hip are not totally triangular, but are cut off so the top is 20 centimetres wide. They are then gathered and smocked to fit in the opening in the side seam. Gathered gores in front and back can be seen on the Moselund tunic, which is from the 11th or 12th century and also on the sides of this 12th century alb.
The gores in the alb are not only gathered, but also has decorative smocking. I also had a go at decorative smocking, though it is no way near the beauty and difficulty of the smocking on the alb, but was my very first smocking.