Zahab has entered guilty pleas to conducting research into the development of a laser warning receiver, as well as rocket guidance for a terrorist organisation between December 2014 and February 2017, when he was arrested.

He has since denounced his support of the group telling the NSW Supreme Court this week that the "nail in the coffin" for his dwindling support of IS was the bombings carried out on churches and luxury hotels in Sri Lanka, in which more than 250 people died on Easter Sunday this year.

Supreme Court Justice Bellew placed an interim suppression order over Zahab's evidence on Monday after defence barrister Malcolm Ramage, QC, raised concerns for his client's safety.

But the order was lifted on Tuesday after Mr Ramage said Zahab wanted his sentiments to be made public.

Zahab has also pleaded guilty to refusing to comply with an order to provide investigators with passwords to access encrypted data on his phone following his arrest in Young in February 2017.

From December 2014 Zahab researched and constructed laser warning receivers using information from a US website and by sourcing easily obtainable components.

He compiled a 288-page report providing detailed instructions on building the devices and sent it via encrypted software to a UK national later revealed to be a member of Islamic State.

He also designed missiles using a freely available computer program, simulating flights of projectiles, some emblazoned with the Islamic State flag.

Zahab told the court that this data was never sent to Islamic State, but "probably" would have been "had the opportunity arose".

Zahab said he began devouring IS propaganda on social media in the wake of the Arab Spring, sympathising with the organisation because of its successes against Syrian President Bashar al-Assad, who he described as a "tyrant dictator".

He said it was only following his arrest and detention in maximum security prison, where he began watching "normal TV" and speaking to imams, that his "world had turned upside down".

"I'm fully embarrassed to have been sucked into what I consider is like a cult," he said.

Justice Bellew said he had difficulty accepting Zahab could be "in a bubble, completely divorced from the fact that here were and have been for some years widespread reports ... about the evils of Islamic State."

"You would have to be some sort of hermit for those reports not to come to your knowledge, surely," he said.

Young Witness