Your basis should be actual photos of various metals industrial elements, nuts and bolts ,wiring , meshes and panels etc.

Try to get your photos with totally even lighting ot will save a lot of problems later, a cloudy overcast day is best but with a fair amount of light, avoid any shadows on your subject like the plague.

Then you can maybe use them as a basis in photoshop, Look up general tuts in photoshop on how to make them tile look better etc but  YOU DO NEED ORIGINAL PHOTOS to kick off with.

Try to get lots of photos of the afore mentioned subjects or anything you think might fit into sci fi textures and try it from there.