According to the article these were 'Imitation' firearms and the man made them as costume props.
Sydney man faces jail over 3D-printed guns | ZDNet (https://www.zdnet.com/article/sydney-man-faces-jail-over-3d-printed-guns/)
A Sydneysider facing possible jail time for making replica guns with a 3D printer has claimed he had no idea his hobby could land him in such trouble.
Sicen Sun, 28, was arrested in 2017 (https://www.zdnet.com/article/sydney-man-tried-to-sell-3d-printed-gun-for-au1m-report/) after he advertised one of his imitation weapons for sale for AU$1 million on a Facebook buy, swap, and sell group.
Just be aware of what can get you into trouble folks.