Is it possible that Walter just doesn't remember building the machine because of the pieces of his brain that were removed?
Yes especially if you have not built it yet. The point I was trying to make was that If Walter had made the machine he would still be familiar with his own signature. He would see that in the device if indeed he had made it.
It's easy to forget that Astrid is the lone normal person working in close quarters with a bunch of weirdos. - Tim Surette