He has previously worked with interaction through the creation of board games and sound sculptures and is keenly interested in the relation between reactivity and adaptivity. He has been an active part of organizing and creating installations at the science festival in Gothenburg and creates experimental musical instruments such as the teddy bear orchestra, parasitic music box, fused instruments and a (but not 'the') musical marble machine. Karl-Johan is also part of the improvisational band "Ljudlabbet" (The Sound Lab).