Sicen Sun, who once enjoyed a successful career in advertising, says he only intended for the replica firearms - which included an imitation sub-machine gun seen in Stargate - to be used as costume props.

"I could not even begin to contemplate that a hobby would land me in such strife,"' he told a sentence hearing earlier in August.

The 28-year-old was facing the prospect of jail time but Judge Penelope Wass on Tuesday handed him a 12-month suspended sentence after finding the overall risk he posed to the community was slight.

She said the replicas, which were substantially similar in appearance to real-life weapons, weren't capable of being loaded with ammunition.

"They were being used in fantasy role-play games," the judge said.

Sun had pleaded guilty to charges including manufacturing a pistol without a licence permit, possessing an unauthorised pistol and the NSW first of possessing a digital blueprint for the manufacture of firearms.

He was arrested in April 2017 after he posted one of his imitation weapons for sale for $1 million on a Facebook buy, swap and sell group.

Police found several replica guns and more than 400 digital blueprints when they searched his Waverley home.

The court heard he'd been grappling with a gaming addiction which developed in the lead-up to his parents' deportation to China in 2015. They were sent back despite concerns for their safety and costly appeals.

Sun said creating props and costumes helped fill a void in his life and he didn't appreciate the severe consequences of not holding a permit for the replicas.

The judge accepted he never intended to sell his Facebook-listed imitation, but noted that if one of his creations fell into the hands of criminals "it could be used to invoke fear of it being a genuine weapon".

"The replicas were not stored securely in the offender's home making them arguably more likely to be stolen and fall into the wrong hands," the judge said.

She said Sun had been assessed as having a low risk of re-offending and was now all too aware of the consequences of possessing replica weapons.

He told the court earlier this month that he had distributed pamphlets warning of the legalities of 3D-printing costume props.

"If someone had done it for me, if someone had told me just the full extent of the offending behaviour that I was committing by printing these things, I wouldn't have done it," Sun said.

Asked outside court on Tuesday what he would say to people wanting to make 3D guns, Sun said: "Don't do it."

Australian Associated Press