These dresses aren't actually made of blood, but they are made of something just as weird: red wine. Either way, this is weird. Sciencey-types in Australia have discovered that, when a specific bacteria is added to red wine, the wine takes on woven, cotton-like texture that can create seamless, stitch-less cloth. That cloth just happens to look like a layer of congealed blood when worn.
From OddityCentral.com: The process of creating wearable fabric from wine starts by adding a bacteria called acetobacter to batches of red wine, to convert it into vinegar. A scum-like layer forms on the surface of the wine, in the process, which is harvested and dried on an inflatable mannequin to get the desired shape. After it has dried, the mannequin is deflated, but the fabric retains its shape. Sounds pretty simple so far, but there is one major downside to this wine-made clothing. When it dries, the fabric becomes as fragile as tissue paper and tears very easily, so the clothes have to be kept damp when worn.