Maddi's mum Anita Barnett's face had a huge smile on her face the entire time.
"This is Christmas... I'm just so blown away," she said.
Maddi's sister Lilli, 14, was also kept in the dark about the surprise and enjoyed riding in hot rods and motorbikes.
"Lilli is such a petrol-head," Barnett said.
"And Maddi is very into animals and nature... she absolutely loves dragons and I always say she has the spirit of a dragon."
Everyone who took part in Maddi's surprise brought a gift or a donation for the family.
Maddi and Lilli chose a couple each and the rest will be donated to the Ronald McDonald House in Grafton Mews.
However, Barnett said Maddi and Lilli have never been focused on gifts.
"They have always wanted to pull people together, they really are amazing and always have a smile at the end of the day."
Barnett said things had changed a lot for their family since Maddi's diagnosis in April.
"It's all about the girls now."
A Givealittle page has been set up to help the family fulfil Maddi and Lilli's bucket list, which includes biscuiting at Pilot Bay together.
Organiser Roger Shutte said he was blown away by the amount of support he received with such short notice.
"Being an older guy and Christmas not meaning so much, this response has given me a new faith in community spirit."
The Waihi builder said he was installing a ramp for Maddi this week to make her life easier.
The event was sponsored by local businesses and clubs.
To donate: Visit: https://givealittle.co.nz/cause/maddi
What is a diffuse intrinsic pontine glioma?
Diffuse intrinsic pontine gliomas (DIPGs) are highly aggressive and difficult to treat brain tumours found at the base of the brain. They arise from the brain's glial tissue — tissue made up of cells that help support and protect the brain's neurons. These tumours are found in an area of the brainstem called the pons, which controls many of the body's most vital functions such as breathing, blood pressure, and heart rate.
- Boston Children's Hospital
