Any funds would also be used to create a bursary for the children's education.
"Sadly the only man in their lives is their grandfather," Herbert Miller said.
"I therefore plea for generous donation to be able to secure a future for these children."
Miller died when he visited friend Josh O'Neill's house on Universal Drive to weld a new exhaust manifold on to O'Neill's Holden WB Kingswood car.
When Miller arrived he was excited to tell O'Neill he'd managed to store two components of oxy-fuel, oxygen and acetylene, into one LPG bottle.
The two are normally kept in two bottles, each of which has a regulator, the two components meet at the welding torch causing the chemical reaction used to cut or weld.
"He didn't realise he had made a bomb," O'Neill said.
Miller was a keen soccer player, Christian and family man.
"He was a family person. He loved his wife and his three kids," said best friend Stacey Leth.
"He loved his job, he loved welding, he loved having fun. He was always laughing."
Both men came from South Africa, but met in Auckland.
Howard and his wife Abigail were regular church-goers.
"He was very religious, he loved God," Leth said.
"He was a good soccer player. He always played privately with friends.
"He also loved to dance. He was always dancing - a very positive man.
"He was the type of person who, if someone said something wrong to me or to him, he would say, 'Oh, don't worry about it'."
