Before getting to the museum itself, it's worth getting clarity on some Czech names. 'Šumava' translates as 'Bohemian Woods', and there are three such museums, in Kašperské Hory (German: Bergreichenstein), in Sušice and in Ζelezná Ruda. It is the first of these three that interest us here.

Muzeum Šumava, Kašperské Hory

Muzeum Šumavy, Kašperské Hory, contains most of the paper pattern archive of the Loetz factory (not open to the public) and a substantial and interesting collection of Loetz glass, including several spectacular pieces such as these three huge lampshades:

Moreover, it is the only source where one can obtain copies of the important Loetz/Series II, Paper Patterns for Glass from 1900 to 1914, by Jitka Lněničková. (Thank you, Christian, for taking so many trips to Kašperské Hory to obtain books for us.)

Not only is the museum very well worth a visit in its own right, but it is just a short distance from Klášterský Mlýn, the site of the original Loetz factory, where you can see von Spaun's villa (designed by Leopold Bauer) and search for glass shards on the banks of the Otava River. One suggested itinerary for a Loetz-oriented trip to the Czech Republic would be to start in Prague, drive about two hours to Klatovy, another one to Kašperské Hory, and then two more to Passau, just over the German border. 

Von Spaun Villa, near Kašperské Hory