English brothers Alan and Michael Perry, who helped Sir Peter with modelling on The Lord of the Rings, created the miniatures.
The former New Zealand Defence Force Chief of Staff, Lieutenant General Rhys Jones, is organising the diorama at Sir Peter Jackson's request, but balked at the idea of "contracting out" the painting, according to Marauders wargamer Vince Cholewa.
"It's a New Zealand commemoration, why don't we get New Zealand to do it," said Mr Cholewa. "So the idea was to get 100 people around the country doing it."
He said the wargamers had been supplied with specifications, while an online blog among gamers provided advice - including some posted by Sir Peter.
"I've been looking at your work as it's been posted on this blog, and it's terrific," posted Sir Peter.
"My only suggestion would be to vary the colours of the New Zealand shirts a little more. There are no photographs of the Wellington Battalion on Chunuk Bair, but we know the attack orders from General Godley specified "shirt-sleeves only".
Sir Peter said he encouraged the painters to "mix it up a bit", rather than be meticulous with accuracy, suggesting that grubby white shirts, olive greens, dark blues, light greys, to give the diorama an accurate look.
"Far from stepping off the parade ground, by August the Anzacs were known as "The Scarecrow Army"," he said.
"Thanks to your efforts, we'll be able to create an accurate and lasting impression of the struggle Kiwi soldiers found themselves in, mid-morning on August 8th, 1915."
It's a change of routine for the wargamers, who usually spend their sessions doing battle with period miniature armies, WWI fighter planes, or even a dystopian Steampunk navy.
Wargamer Ceilidh Evemy, of Masterton, said it was an important project to remember what had happened and pay tribute to the men who lost their lives.
She said the figurines feel "huge" in comparison to the 15mm figures she usually worked with.
Her grandfather had served in World War I but contracted a disease and was invalided to quieter duties.
-See mastertonmarauders.blogspot.co.nz for more information.