Hey Kristof!
I think it’s ok if you submit a digital version of the exercise. In the end, sculpting cloth in 3D can be just as trick as doing it in clay, because mirroring for symmetry isn’t really an option here 😉
Just upload the images of your results accordingly.
If, however, you ever feel like you’d want to get your hands dirty with clay, we do offer something to help that process along 😀 – The SculptBox!
Anyways, happy sculpting!