"It was the coolest show I had ever seen," Nilsen told Guinness World Records of his first time watching the live-action superhero television series in 1993.
The collection began when Nilsen's uncle bought him a Megazord figure from Mighty Morphin Power Rangers Season 1 for his 10th birthday that year.
At first, Nilsen said, he was "significantly disappointed" with the toy.
"It didn't combine or transform as I hoped and it was the smaller version with shooting fists," he said. "I was so disappointed, I didn't even ask for Power Rangers items for Christmas."
His introduction to a deluxe Megazord toy five months later inspired him to keep looking at what other Power Rangers toys were available.
"It combined and transformed, just like in the show," Nilsen said. "It was incredible. I didn't think they made such a thing."
Today, Nilsen's collection, which was counted before this year's release of Power Rangers: Dino Fury Season 29 on Netflix, includes a special edition Soul of Chogokin Megazord valued it up to $400 and the complete collection of the "World's Smallest" Power Rangers action figures.
"Whatever you can think of, I probably have it," Nilsen said.