unity
abstract
accuracy
background
binding
bond
brass
bronze
brown
business
circle
clock
clockwork
cogs
cogwheel
concept
connection
cooperation
engine
engineering
gearbox
gears
gold
grunge
industrial
inside
interlock
invention
machinery
macro
mechanics
mechanism
metal
old
power
precision
progress
reliability
rotate
rustic
stylized
team
teamwork
technology
time
toned
turn
vintage
watch
wheel