What were they made of? They must've been rather difficult to make, especially being that most pictures show them to be an extremely high quality. Would they have been relatively tight like spandex, or relatively loose fitting. Are there any examples that have survived to the modern era and can be looked at?
I'm not a garment historian, but since this question has gone unanswered for a while I'll have a stab. The garments you're thinking of are hose, which are generally more like modern stockings, and the depictions of them in art are generally quite accurate. They were made of wool, generally. This article (PDF) on how to make reproductions of later period fitted stockings gives some idea how they were shaped.