The protest, organised by five pupils calling themselves the "social justice group", is drawing attention to companies such as Samsung, which makes tanks as well as MP3 players, and Toshiba, which makes laptops and missiles.
Group member Kathryn Darling said the group wanted pupils to consider the ethics of manufacturers, as well as the price and features of consumer goods.
"So, if someone isn't supportive of warfare then that might be something that determines whether they want to buy that product or not."
Representations of landmines had also been spread around the school and the protest had attracted much interest, she said.
"Most people haven't thought about any of this sort of stuff before, so I think it is leaving quite a mark in people's minds."
St Hildas principal Melissa Bell said she had no objection to the form of the protest.
"It is a strong message, but then it's a real issue so I have no problems with it."
Behind the scenes, the group has been advised by Jolyon White, who earlier this year spent a month living in the Dunedin town belt to draw attention to poverty.
Mr White said a 2007 United Nations report stated that a third of those living in poverty were in countries where there was conflict or a collapse of the state.
The issue is to be discussed at school assembly this morning.
