They are two of eight New Zealanders set to compete at the International Paralympic Committee world championships in the Middle East country of Qatar later this month.
Four other Taieri athletes - Holly Robinson, Rory McSweeney, Caitlin Dore and Will O'Neill - are also in the New Zealand team, which left for Darwin for a training camp yesterday.
The squad spent the past 10 days in camp in Dunedin, and competed at the first two track and field meets of the season at the Caledonian Ground.
In addition to competing and training, they took part in team bonding activities and spent plenty of time in the heat chamber preparing for the climate in Qatar's capital city, Doha.
Hamill (25), who has cerebral palsy, won silver at the 2010 Delhi Commonwealth Games in the shot put, and had a productive camp.
She extended her own national record in the F34 class by a whopping 25cm with a 7.14m put at the Caledonian last weekend, and is on track to push for a spot on the podium at the world championships.
Hamill is not long back in the sport, after taking a couple of years off to focus on life outside of shot put after the Delhi games. Since returning, a rule change means she no longer needs to stand up to compete.
''There was a big rule change, which was to my advantage,'' Hamill said.
''I used to stand up, but now I get to sit down. It's a lot fairer, and it's also a single class. I'm not mixed with all these other disabilities. It's so much better.''
Hamill is aiming for a new personal best in Doha, and hopes that leads to a medal.
Grimaldi (18), who was born without a right hand, will compete in the 100m, 200m and long jump in Doha.
When competition gets under way on October 22, it will mark two years since Grimaldi first tried athletics at an AWD camp in Dunedin.
She quickly warmed to it, and holds national para records in the T47 class in long jump (5.29m), 100m (13.58sec), 200m (28.24sec) and 400m (64.26sec).
Grimaldi, who has never competed outside New Zealand and Australia, said it was surreal to be asked questions about competing at the world championships.
''It's pretty crazy,'' she said.
''If you asked me at that camp we first went to, I would have said, `No way, don't be stupid'.
''But it's just come along so quickly. It's been a crazy two years.''
Grimaldi, a quantity surveying student at Otago Polytechnic, spent much of winter working on speed and strength at training, and said she has noticed the hard work starting to pay off.
She is cautiously aiming to finish in the top six at Doha.
