Tasmania Police Detective Inspector Kim Steven said it was important homemade firearms were handed in through the ongoing gun amnesty.

When asked if homemade guns were common in Launceston the detective inspector said: "You don't know what you don't know, so that's where we need the public to help us get these off the street."

Timothy Gardiner died in his mother's arms after being shot by an unstable homemade firearm in the chest at Ravenswood on May 18.

Detective Inspector Steven said the gun looked like a small handheld torch.

"A single shot from a thing that looks quite innocuous can be deadly," he said.

"They are homemade guns, so they don't go through the same rigorous process as a manufactured gun and all the regulations that go with that so there's that difficulty."

A gun amnesty is being held at Churchill Park, Invermay on May 30.

Anyone with unwanted, unregistered, illegal or homemade firearms can drop them off between 9am and 5pm.

There are no penalties for surrendering guns during an amnesty, with police accepting the firearms without question and destroying them.

Detective Inspector Steven said homemade firearms were unsafe and people should use the Invermay amnesty or call police to arrange for their unwanted guns to be collected.

"People come via firearms a number of different ways - through deceased estates, taking over a house and finding one in the shed," he said.

"Some people panic and think 'what are they going to do', but just ring us and we'll pick it up.

"The less that are out there the better."

Tasmania Police has never confiscated a homemade firearm created using a three-dimensional printer, Detective Inspector Steven said.

For more information about surrendering a gun, call police on 131 444.