A keen mountain biker, Duval was also talented behind the lens of a camera and had ambitions to become a wildlife photographer.
More than $24,500 had been donated by around 440 contributors to a Givealittle page set up to collect donations towards the funeral service for Duval.
Duval's funeral would be held at 11am on Thursday at the Whangaparāoa Baptist Church.
Any donation money spare from the funeral would go towards a photography scholarship at Whangaparāoa College, where Duval was a Year 11 student, and towards a mission project he was supporting in the Philippines.
Longtime family friend Molly Kirkbride set up the page on behalf of the Duval family and was astonished at all of the support.
"It's gone nuts," she told the Herald today. "This morning I woke up and it was on $20,000 and now it's nearly $22,000 or $23,000."
By 4pm, more than $24,500 had been donated to the Givealittle page.
The Duval family was heartbroken by the loss of their son, Kirkbride said, but the tight-knit Whangaparāoa community had rallied around them.
The teenager's father, Stu, alerted Facebook friends on Sunday morning about Duval's passing.
"It is with incredible sadness and a broken heart that Lynette and I share with you the sudden passing of our dearest Louis last night," he said.
"He was greatly, immeasurably, loved and his 15 years with us were special beyond words. Go well my son, in God's hands now."
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Kirkbride said she would remember Duval as a "bright and creative" person.
Elsewhere, tributes flooded social media since Duval's death.
"He will be missed by so many," shared a friend, while another described him as upbeat, funny and sarcastic.
Another described Duval as the "most amazing, kind, creative and wonderful young person you could imagine."