Friends Benji Egan, Sammy Moore and Flynn Montgomerie used Lego to build a haunted house to display at the show.
Benji said the three Tainui School pupils spent many lunch breaks planning the project.
"We wanted to make something cool and use all our skills."
A haunted house allowed them to design a structure with many interesting rooms.
Each boy built a floor of the house, he said.
Flynn said people at the show should give the build their "people’s choice" vote because "it took so long and it’s an amazing build".
Flynn said he had loved playing with Lego "since I was really little" and enjoyed its endless possibilities.
"You can make anything."
Lego Users Group Otago chairwoman Jacqui Hay, of Company Bay, said more than 40 exhibitors were expected at the show.
The show was one of the first family events in Dunedin since Covid-19 hit, Mrs Hay said.
The show includes performances from magician Jonathan Usher, children’s entertainer Rainbow Rosalind and science educator Amadeo Enriquez Ballestero.
The event, hosted by the group and supported by Rotary Dunedin Central, would raise funds for the Child Cancer Foundation to support children in Otago.
Dunedin Brick Show is on at the Edgar Centre 10am-5pm on Saturday and Sunday.
