David Lia confessed last year to building a home-made device in the basement of his house, which he planned to detonate at the medical centre as payback against a doctor he blamed for contributing to his blindness.

Lia spent more than a year sourcing the ingredients and parts to build the device, consisting of four cylinders with two timers.

His plans were thwarted when his estranged wife found the bomb hidden in a backpack in their garage while he was overseas.

Lia sat in silence in the dock in Wollongong District Court on Friday as presiding judge Paul Conlon detailed the decline in his mental state over the past decade and his obsession with enacting his so-called revenge.

The court heard Lia had been to see the doctor in 2002 about an incurable eye condition, receiving a special procedure that he later blamed for his deteriorating eyesight.

Further visits to the same doctor in 2008 reignited Lia's anger, and his former wife told police Lia first spoke about wanting to kill the doctor the following year.

He spent time in Shellharbour Hospital's mental health unit and was placed on medication.

However, the woman said a few months after his release she found a note he'd written saying "hire a hit man".

In November, 2010 the couple split and Lia moved to southern NSW, but would return to see his children, staying on the ground floor of the two-storey Albion Park home.

In late 2011 and early 2012, Lia made two online purchases for three kilograms of potassium nitrate, a key ingredient used to make explosives, and in early 2013 he bought items for the bomb at Supercheap Auto in Fairy Meadow.

Police received a tip-off about a possible attack on the doctor in early April last year and turned up at the Albion Park home looking for Lia.

However his wife, fearing what her husband might do to her, told police he wasn't at the premises.

The following day Lia flew overseas on a one-way ticket.

Four days later, the woman discovered the bomb in the garage, prompting her to call police.

Police bomb squad technicians described the device as "elaborate", saying it was capable of detonating.

During a search of the house, officers seized several items associated with bomb making, as well as Nazi paraphernalia, including a swastika flag and documentation admiring Adolf Hitler.

Judge Conlon said whilst in custody Lia had been assessed by psychologists, who had diagnosed him with paranoid personality disorder, punctuated with delusional beliefs.

The doctors said Lia believed people were "out to get him", adding when he was in a state of active psychosis he posed a "serious risk" to the community.

Judge Conlon conceded that determining Lia's punishment had been a very difficult sentencing exercise, given the extent of his mental illness.

He sentenced him to a non-parole period of 20 months, backdated to his incarceration in August last year.

Lia will be eligible for supervised parole in April, 2015.