Zandvliet started the gallery Galerie Slaphanger. This was a small gallery with mostly exhibitions of amateur artists. Also this gallery became a selling point for self published comics and music. After moving to a new building the self-published products became more important. From all over the world people sent their self made and self-published art to Gallery Slaphanger. The gallery became a stronghold for underground music, noise, literature, art and comics. Small concerts were organised, poetry nights, lectures, exhibitions, movie nights and a festival called “het plaatendraaiersfestival” (The record player festival) where people could bring their own old records and play them for the visitors. Galerie Slaphanger stopped existing in 2003.
Artists exhibiting in the gallery were, among others: Chris Berg, Tom Oomes, Eddy de Waal, Bas van Tuyl AKA Bombastus, Marc van Elburg, Koen Hottentot, Nar=me, SAGE art, Sjef Henderickx, Itam van Teeseling, Arjen de Jong, Monique Veldhoven, Damy van der Waal, Rocket Freudenthal, Timex, Joost Geertsma, Jan Tromper, Jollen van der Zwan, Tommy de Roos, Daan van Eijndhoven, Guido Jelsma, Jason Austin, Marc Dancey, Maaike Hartjes, Barbara Stok, Anja Ranja, Wilco Wenrich, Koen Kuijpers, Claudio Parentella, Maria Colino and many others.