Two staff members raised the alarm as the fire quickly took hold and flames rose 3m above the roof.
Thousands of dollars of equipment, including a $1500 sander bought three days ago, automotive hoists and drill presses, accumulated by head of technology Bob Pipe over 20 years of appealing to local businesses, also went up in smoke.
Five trucks from Whangamata, Pauanui, Tairua and Waihi spent two hours battling the blaze.
Mr Preece estimated the cost of replacing "the best workshop" in the area to be in excess of $1 million.
"It's a fantastic resource ... The sad thing is Wintec had been starting an outreach programme for high schools and they were interested in us hosting it at our school because of the facilities we have," he said.
The school was now reliant on the Ministry of Education and its insurers to "do the right thing and put it back to the state it was".
Police were at the school yesterday investigating the blaze.
Detective Sergeant Martyn Hughes of the Thames-Coromandel CIB said early investigations indicated the fire was not suspicious.
"To date no accelerant has been identified and there is nothing to suggest the fire was malicious, however the investigation will continue to be treated as an unexplained fire until such time as we have information that determines what has occurred."
Eastern Waikato fire risk management officer Ross Fleet said it was possible the fire could be malicious and all would be revealed after the investigation.
"The process of the investigation has eliminated a number of electrical causes."
His investigation was due to be completed yesterday but Mr Fleet said the cause of the fire might not be confirmed for a couple of days.
Demolition of the gutted building is set to begin next week - a task which Mr Preece said would cost about $95,000.
"It was built in 1987 but it was built really well, with all the bells and whistles and the head teacher, Bob Pipe, had gathered state-of-the-art equipment.
"Now we just want the ministry to rebuild it so we have a facility as good as we used to have."
Mr Preece hoped work would be completed by the start of term two next year as the facility was also used by students from Hikuai, Tairua and Opoutere schools.
Additional reporting, APN