Student Theses
Before listing some concrete problems -- that I think can be a nice bachelor/master thesis -- I would like to comment on our mutual expectations out of a thesis.
A student thesis depends not only on my own areas of interest, but also on the background and interests of the student. So in principle we can find a common problem of interest to work on that is quite different from what is listed here. Depending on your level the outcome of a thesis can vary from understanding some research level project (bachelor thesis) to becoming an expert in some particular area of research (PhD thesis). Some theses can be finished by implementing some research ideas into concrete software.
Independent of the scale and final outcome of a thesis that we may mutually agree upon, it is expected that at the end you have learnt about methods and objects that are of theoretical as well as practical importance. In general, they will relate to geometry and polyhedra.
Here are some concrete problems for bachelor/master thesis.