英文關鍵字
abstract
background
circle
circular
clockwork
closeup
concentric
concept
design
detail
engineering
equipment
factory
gray
grey
industrial
industry
iron
loopable
machine
machinery
mechanic
mechanical
mechanics
mechanism
metal
metallic
motion
nobody
objects
part
rotate
rotation
simple
solid
spin
spinning
steel
technology
texture
transmission
wheel
work
workshop