Cantwell's first credit came on Stanley Kubrick's 1968 sci-fi movie 2001: A Space Odyssey.
Star Wars creator George Lucas then asked him to design and make prototypes for the Death Star, X-Wing, TIE fighter and Imperial Star Destroyer.
Cantwell's cousin Shannon Eric Denton said he "brought a lot of joy to the world with his art".
Denton added on social media: "And for all of us that knew him he brought a lot of joy being himself."
