Since 2002, Holzer has given almost 200 experimental sound performances, created scores of unique instruments and installations, and taught over 130 workshops in sound art, basic electronics, field recording, and pure data programming across Europe, North and South America, and New Zealand. One of his many notable projects is "Tonewheels," an experiment in converting graphical imagery to sound, in which transparent tonewheels with repeating patterns are spun over light-sensitive electronic circuitry to produce sound and light pulsations and textures. Inspired by some of the pioneering 20th century electronic music inventions and developed in residencies at Tesla in Berlin DE and STEIM in Amsterdam, the all-analogue set is performed live without the use of computers (using only overhead projectors as light source, performance interface, and audience display), and aims to open up the 'black box' of electronic music and video by exposing the working processes of the performance for the audience to see.

Holzer's recorded work has been released via the Nexsound, Mandorla, Sirr, and/OAR, and Gruenrekorder labels, and he has co-initiated several internet projects for field recording and collaborative soundscapes including Soundtransit.nl.  In 2014 he was awarded a working grant from the Foundation of Lower Saxony at the Edith-Russ-Haus for Media Art in Oldenburg, Germany.

Holzer returns to CTM Festival following his presentation of "Probing the Past: A Media Archaeology of Handmade Electronic Sound" at the MusicMaker's Hacklab in 2014.