From what I read, from someone who has received the first issue, the ships are die-cast with some plastic parts.
Originally Posted by TheTooN
1st subby pack arrived this morning. Enterprise D + mag. Couple of pics to show the high level of detail and one next to a BSG Titanium and Hawkeye for scale. I'm well pleased with it overall and look forward to having a fleet
Saucer section is die cast with a plastic hull and nacelles. Die cast base and plastic stand. Overall a nice weight to it.
Couple of small niggles - One of the Nacelle's was loose but as its a plastic part it just clips back in place. Beats lead any day on that score. Also the felt covering on the base isnt straight and one side overlaps and is visible as pic. Nothing horrendous as its only on one side so you can just rotate the base 180 for display. Wee bit sloppy for issue 1 though.