Gruffudd, who won acclaim for portraying the abolitionist William Wilberforce in Amazing Grace and reprises his role as Reed Richards this summer in Fantastic Four: Rise Of The Silver Surfer, joins Neve Campbell, Brian Cox, Roger Moore and Brian Blessed.
Filming is due to wrap in the UK on Apr 20 on the project, which combines computerised animatronic characters with miniatures and centres on a crime-fighting cyborg who must destroy a defective megalomaniacal prototype. Fantastic Films International holds worldwide rights.
Sean Robinson makes his feature directorial debut and Barrie Robinson and Tony Ludwig, whose credits include Starsky & Hutch and Deep Blue Sea, are producing. Jez Harris's Crawley Creatures provides the puppeteering and animatronics.
'It's amazing,' Gruffudd said of early footage. 'This is a whole new format of animation, which is a combination of merging the latest technology with the traditional way of making movies. The result is incredibly unique and so cool.'
'We are creating a live-action environment in miniature that on film appears real and full scale,' Fantastic Films principal and Agent Crush executive producer Fred deWysocki said.