abstract background blue grunge iron metal metals old oxide rust rusted rusting rusty steel structure texture wheathered big construction corrosion heavy huge nut nuts thread threads tool tools diamond free image painted peeled photo plate stock weathered bolt bolts cage grill machine machinery mesh Nuts and Bolts textures weld welded welding black burst chap crack fissure fracture oil paint pattern split tin tinware white backdrop dark decay design gloomy grungy metal background plates rough sheet speckled textural textured urban cut dust dusty gap gaps handsaw nature pile power saw sawdust tree trees trunk wood