 Prop master Rob Smith joined the series during its second season , and had to quickly learn about all the gadgets featured in Fringe 's debut season . Smith was asked to create a " neural stimulator " in the script to " Momentum Deferred " , but " didn ’ t really know the episodes well enough to say , ‘ Oh , ok , that ’ s exactly what it is . ’ So I talked to the director , who had been on season 1 , and he goes , ‘ Oh , I don ’ t know , it ’ s just something that goes on the guy ’ s head ' . " Smith discovered that the headpiece in question had been rented during the first season , causing him to recreate the prop over one weekend . He called this process " a little bit stressful . " The gadget , Smith explained , was important because it " defined the way that Walter works . He ’ s this mad scientist who takes conventional science and then puts his own twist on it , as it were . And then the thing that struck me about that one was that it made me uncomfortable to look at it . " Smith added , " It ’ s one of those things that people love and hate about Fringe , it puts your [ sic ] out of your comfort zone . That ’ s sort of what I was trying to say about Walter … there ’ s kind of a bird ’ s nest of wires everywhere , and then they end up on the guy ’ s head , and from that he can tell what the guy ’ s thinking . It ’ s quite cool . " 
