In the Bunbury District Court in April, Ben McDonald Roberts was imprisoned for two-and-a-half years by judge Allan Fenbury. 

But on Wednesday, the WA Court of Appeal voted to reduce his sentence to eight months, a period he has currently served. 

When sentencing Roberts in April, Judge Fenbury said he accepted Roberts meant no harm by his actions and was unlikely to reoffend. 

"It is very, very, important to discourage amateurs from making this substance in the community," Judge Fenbury said. 

"The fact that the ingredients and recipe are so readily available is frightening.

"The court must make an emphatic statement to deal with you in a way that may appear harsh to others but makes an example of you." 

In December 2013 Roberts entered guilty pleas to five counts of making an explosive substance and two counts of unlawfully endangering the life, health or safety of a person.

Defence lawyer Derek Hunter said Roberts, in making the substance, was having a bit of fun and did not intend to harm anyone or cause any damage. 

“The tape of Mr Roberts being interviewed by the police demonstrates he had no idea as to the volatility of TATP,” Mr Hunter said.

“When he was interviewed he did not even realise he had produced TATP, rather he was under the impression he had created Acetone Peroxide.”

The discovery of the explosive material in the estuary by a fisherman sparked a widespread search of the area by the Navy in October. 

The explosives discovered by the fisherman were convoyed to Perth and destroyed at Gloucester Park before a second batch of the substance was found and destroyed in Australind.