Researchers at Dartmouth University have found that a 3D printed shape covered in aluminum foil can improve wireless range and increase Wi-Fi security… reflectors could accurately shape Wi-Fi beams to avoid some spaces and favor others, thereby increasing security and coverage. For example, you could shape your beam to avoid going out a window into the street but be stronger in a room nearby.
My bad. Dad was right. Aluminum foil and antennas work.