McGarry said it would take about five weeks to build and it would easily be the biggest and best slopestyle course ever made in New Zealand.
"By a long shot. The only other slopestyle event we have had in New Zealand was the one we built in Queenstown," he said.
He said the Queenstown event was held in the city and was built on scaffolding. "But this is awesome because we have proper slopes and trees to work with and a decent amount of gradient. And when you have good gradient you can use it to get big air."
When it is completed, the track will include nine features with the biggest jump standing about 3.6m tall (12-foot). It will take riders about 1m 30s to complete the course.
McGarry has ridden slopestyle events for 10 years and both he and Hey have plenty of experience building the tracks.
"I have ridden some awesome courses and I have ridden some terrible ones, and I have learned a lot in regards to what works and what doesn't - and what riders like to shred," McGarry said.
He will be one of the riders taking part in the top event in March and is the best rider from Australasia entered.
"I used to ride motocross and BMX and race downhill mountain biking here in New Zealand, and there was no slopestyle events in New Zealand [back then]. I travelled over to Whistler in Canada during an overseas trip and competed in my first one," he said.
McGarry said he was hooked after that and started getting sponsorship deals.
"I just started doing it for fun but it turned into a job in the end which is rad."
Hey said it was really hard to estimate but he expected they could probably fit 10,000 spectators around the slopestyle track in March.
Crankworx Rotorua director Takurua Mutu said McGarry and Hey, who are both from Queenstown, were world-class track builders. "Hey has built trails for over a decade, and McGarry is an international slopestyle star who was previously a carpenter and as a result has developed his own formula for designing world-class competition trails."
Crankworx Rotorua runs from March 25-29, culminating in the slopestyle event on Sunday March 29 at 12.30pm.
The New Zealand Slopestyle Champs is part of the FMB World Tour which includes the top slopestyle events around the world. Other top events during Crankworx Rotorua include the Australasia Whip-Off Champs, Rotorua Pump Track Challenge, Mons Royale Dual Speed and Style, Rotorua Downhill, and Giant Toa Rotorua Enduro.
Local trail building company Empire of Dirt are building most of those tracks and will be assisted by Descend Rotorua for the downhill course.
There will also be a Bikes and Beats Music Festival, featuring New Zealand's top artists, and a Kidsworx event to get families involved. You can find more details at crankworx.com. To get tickets visit Ticketmaster.