This research aims to extend the boundaries of biomaterials applications into electronics. Mycelium is a fast-growing vegetative part of a fungus which adapts to different shapes when growing in a mold and decomposes after 90 days in a natural environment as organic waste. In order to create more sustainable prototypes, we use mycelium composites with common digital fabrication techniques for replacing plastic in electronics. We present our method for growing mycelium, our design process of using digital fabrication techniques with mycelium, applications for embedding electronics in mycelium boards, making enclosures for electronics, and using mycelium within electronics. This paper could contribute with the merge of biomaterials and electronics, an approach which is still under exploration.