Longlea resident Manning Walsh, 21, North Bendigo man Bryden Ermel, 22, and 22-year-old St Albans resident Michael O'Dowd, 22, each pleaded guilty in the County Court on Friday to attempted armed robbery and three counts of common assault.

Ermel also pleaded guilty to possessing cannabis, possessing cocaine, and possessing a controlled weapon, while O'Dowd entered guilty pleas to additional charges of possessing cocaine and possessing a prohibited weapon.

On the evening of January 25 this year, the three men drove from Bendigo to Castlemaine with the aim of stealing drugs from a teenager Walsh was friends with.

He knew the teenager was returning from Melbourne with drugs that day, and he arranged to meet him when he arrived.

When the offenders arrived in Castlemaine, Walsh went to a gazebo near the railway station to meet the victim, while Ermel and O'Dowd hid nearby, carrying a machete and a butterfly knife respectively.

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While he waited, Walsh sent three text messages to Ermel, one saying, "That's his train" and another instructing Ermel he would tell them when to come.

The intended victim and three of his friends, also teenagers, alighted from the train and went to the gazebo to meet Walsh.

After a few minutes, Walsh made a phone call, and Ermel and O'Dowd approached, bearing their weapons.

They instructed the teenager to put the drugs in a backpack, but he and his three friends ran away, terrified.

Walsh also ran, pretending he too was a victim.

His phone was placed in a nearby Salvation Army bin, by prior arrangement with his co-offenders.

Ermel and O'Dowd drove back to Bendigo, while Walsh and the victims returned to the gazebo.

They called the police and Walsh made a statement pretending to be a victim. He told them his phone was stolen.

But the following day a detective called Walsh's phone - the one he said was stolen - and he answered.

He said he had found it in the Salvation Army bin by using an app.

Police obtained CCTV footage that showed Walsh with Ermel and O'Dowd just prior to the crime.

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In early February, police searched Ermel's address and found cannabis, cocaine and a black-handled knife (not used in the attempted robbery).

Ermel admitted to his role in the crime, and said he felt terrible for what he had done.

Walsh's home was searched that same day, but despite the messages to Ermel, he maintained his innocence.

He said he had arranged to meet the victim to collect Xanax and the others had offered to drive him there.

O'Dowd was arrested outside a milk bar after police called him and he told them where he was.

When police arrived, he admitted to throwing a butterfly knife in a nearby bin.

Police found cocaine at his home.

O'Dowd also admitted to the offending, and said he "felt really bad" for the victims.

On Friday, the court heard evidence from Ermel's father, who detailed struggles his son had faced in recent years, including his mother's cancer diagnosis, the deaths of grandparents, and his parents' separation.

His father said he was now clean of drugs.

Defence counsel Julien Lowy said Ermel had gotten his life back on track, and the offending was an "aberration".

Walsh's lawyer Robert Timms said his client had successfully completed a court program while on bail, and he too was completely drug-free.

He said Walsh's 16 days in custody had been "the most terrifying time" for him and he was frightened of returning to jail.

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Meanwhile, Eleanor Millar told the court O'Dowd had a long-standing problem with drugs which stemmed from the age of 13, when his father suffered a brain aneurysm and moved into a nursing home.

Ms Millar said O'Dowd had a cognitive impairment and was now abstinent from drugs, and the 100-plus days he spent in custody had had a "significant deterrent effect" upon him.

In sentencing, Judge John Carmody said the offending was serious, planned about two days in advance, and committed against "younger and easier" targets.

But he noted the men had pleaded guilty at an early opportunity and were young offenders.

Judge Carmody said he was satisfied the time spent in custody had deterred the men from further offending.

They were each convicted and sentenced to two-year community corrections orders, with 200 hours of unpaid community work and conditions they undertake treatment addressing substance abuse and their mental health.

Ermel was also fined $1000 and O'Dowd $750 for the drug and weapons offences.

"This is your chance," Judge Carmody said.

"Each one of you better pick it up with both hands and take it."

Had they not pleaded guilty, the three men would have faced two years in prison, with a minimum term of one year.