Following Reitman's tweaks to the design, on-screen models were made from a fiberglass shell with an aluminum backplate bolted to a United States Army backpack frame. Each pack weighed about with the batteries for lighting installed, and strained the actors' backs during the long shoots. Two lighter versions were made, a hollow one with surface details for wide shots, and a foam rubber version for action scenes. The fiberglass props were created by special effects supervisor Chuck Gaspar, based on Dane's design. Gaspar used rubber molds to create identical fiberglass shells. The neutrino wand had a flashbulb at the tip, giving animators an origin point for the proton streams. The production used fake walls laced with pyrotechnics to practically create the damage of the proton streams. The PKE meter prop was built using an Iona SP-1 handheld shoe polisher as a base, to which lights and electronics were affixed. The technology was designed not to be overly fancy or sleek, emphasizing the characters' scientific backgrounds combined with the homemade nature of their equipment.