I used a Halo base figure and 3D customized the head, arm tentacles, chest logo and back tentacles. They were not purchased online but made here in-house. Painted with army painter acrylic paints (primed/cleared with Mr Hobby sprays). The background diorama books are Flip Scene Studio books (found on eBay). I paint the suit black then dry brushed silvers to make it appear like metal, adding in some dark purples and variant grays to give suit dimension. For venom tentacles, I painted them black, dry brushed with silver a little, then paint washed over them with a dark blue so they symbiote parts stood out a little different than the suit. It came out really cool. Painted the eyes white and used a blue paint wash to outline them. Used a color called "mummy robes" instead of white for the teeth, claws and bonish parts of tentacles. Purposely wanted to see both sets of hands as if the original soldier is still there but Venom is coming out around him. Here's a backstory to imagine:

"The mech soldier stood rigid, its armor scarred and darkened, but something alive now pulsed beneath the metal. Black tendrils crawled over its shoulders and coiled from its back like living cables, while its hands had warped into clawed, shifting weapons. Behind the cold structure of the suit, a monstrous face pressed through—white eyes glowing, a jagged red grin stretching across the helmet. The man inside was still there, guiding its stance and purpose, but the Venom symbiote had taken hold, turning him into a silent, predatory fusion of discipline and hunger, ready to strike without warning."

Enjoy!