機器
aging
antique
background
bolt
brown
close up
color
concept
construction
copy
dirty
effect
engineering
equipment
factory
fastening
heavy
hexagon
horizontal
idea
industrial
industry
iron
large
macro
material
metal
metallic
nut
object
obsolete
old
out
past
process
retro
rough
rust
rusty
screw
steel
strength
sunlight
surface
thick
tool
uneven
weathered
work