Since acrylic and glass pieces seem unobtainable, i may try to use a mountain crystal cluster ("Bergkristallgruppe")

http://www.shop.hde.ch/cgi-bin/shop/front/eidamo.cgi?func=anzeige&wkid=1523135365599062&rub1=Bergkristall Kristall&rub2=Bergkristall Gruppe

I may visit that shop or http://www.welt-der-kristalle.de or http://www.kristallkeller.de/.

In fact it seems there are many mineral traders around, but those are the nearest.