A lora in the style of H.R. Giger, trained only on his artwork.
V4 is the best version so far, I feel pretty safe in saying its best overall.
Prompting: Terms like biomechanical, industrial, airbrush, monochrome. Try starting out with something like "Highly detailed traditional artwork by H.R. Giger of..."
V2 and V3 are based on a different set of images and training, may be better or worse for your needs.