A total of 41 schools and about 2000 pupils will present their best Lego works to attendees, with one winner to rule them all.

Grade 5 pupil Ptolemy Torney will represent Launceston Preparatory School with his Lord of the Rings inspired creation.

"Basically it is a scene from the third Lord of the Rings movie, it is of the Black Gate of Mordor," Ptolemy said.

"I just love building Lego I do it pretty much all the time and I loved the Lord of the Rings movies and the books when I read them.

"I think that they're really interesting, I just love Lord of the Rings so I decided to do it."

Entrants need only follow a few basic rules: their works can't be made from a Lego kit or instructional manual and their creation cannot be more than 52 square centimetres. 

Brixhibtion coordinator Ken Draeger said the event was a great way for kids to show their Lego skill.

"That's why we do the competition, to inspire kid's imagination and ingenuity," Mr Draeger said.

Ptolemy said he was excited to see what everyone else had built for the exhibition.

"Ever since I saw the Brixhibition it was just about my biggest dream to actually enter into it so I was really happy," he said.