There are very few people these days who still make medieval-style complex weaves, and one of them is Sylvia Wiechmann, who runs a weaving workshop in Munich. She made a reconstruction of a type of samite called "Kölner Borten" a while ago, and has a video on Youtube showing how they are made, and explaining the process. In German - but maybe watching it is still interesting for you even if you don't understand the text: