diff --git a/config.lua b/config.lua
index e7d9000..ebad9c3 100644
--- a/config.lua
+++ b/config.lua
@@ -3,3 +3,9 @@ Config = {
     gridOffset = 0,
     portWidth = 16
 }
+
+Color = {
+    input = { 0.8, 0.3, 0.3, 1 },
+    output = { 0.3, 0.3, 0.8, 1 },
+    mechanism = { 0.8, 0.8, 0.8, 1 }
+}
diff --git a/selector.lua b/selector.lua
index e55713c..bc77724 100644
--- a/selector.lua
+++ b/selector.lua
@@ -11,7 +11,18 @@ local mecha2 = Mechanism:new( GridPoint:new(10, 5), GridPoint:new(2, 2), { port1
 
 local mecha3 = Mechanism:new( GridPoint:new(13, 5), GridPoint:new(2, 1), { port1:clone(), port2:clone(), port5:clone() }, {1, 0.5, 0.5, 1} )
 
-local mechs = { mecha1, mecha2, mecha3 }
+local conveyorPortI1 = Port:new( GridPoint:new(-1, 0), PortRotation.left, Color.input )
+local conveyorPortI2 = Port:new( GridPoint:new(0, -1), PortRotation.up, Color.input )
+local conveyorPortI3 = Port:new( GridPoint:new(0, 1), PortRotation.down, Color.input )
+local conveyorPortO = Port:new( GridPoint:new(1, 0), PortRotation.right, Color.output )
+local conveyorMecha = Mechanism:new( GridPoint:new(0, 0), GridPoint:new(1, 1), {
+    conveyorPortI1:clone(),
+    conveyorPortI2:clone(),
+    conveyorPortI3:clone(),
+    conveyorPortO:clone()
+}, Color.mechanism )
+
+local mechs = { conveyorMecha, mecha2, mecha3 }
 local actions = { 'none', 'first', 'second', 'third' }
 
 local selected = 0
diff --git a/timer.lua b/timer.lua
new file mode 100644
index 0000000..7fa4f01
--- /dev/null
+++ b/timer.lua
@@ -0,0 +1,78 @@
+local function defaultTimeout() end
+
+---@class Timer
+---@field duration number
+---@field time number
+---@field oneShot boolean
+---@field timeout function
+---@field data table
+---@field paused boolean
+Timer = {
+    duration = 1,
+    time = 1,
+    oneShot = false,
+    timeout = defaultTimeout,
+    data = {},
+    paused = true
+}
+
+---@param duration number|nil
+---@param oneShot boolean|nil
+---@param timeout function|nil
+---@param data table|nil
+---@return Timer
+function Timer:new( duration, oneShot, timeout, data )
+    local timer = {
+        duration = duration or self.duration,
+        time = duration or self.duration,
+        oneShot = oneShot or self.oneShot,
+        timeout = timeout or self.timeout,
+        data = data or self.data,
+        paused = self.paused,
+    }
+    setmetatable( timer, { __index = self } )
+
+    return timer
+end
+
+---@param dt number
+function Timer:tick( dt )
+    if self.paused then
+        return
+    end
+
+    self.time = self.time - dt
+
+    if self.time <= 0 then
+        self.timeout( self.data )
+
+        if self.oneShot then
+            self.paused = true
+            self.time = 0
+        else
+            self.time = self.duration + self.time
+        end
+    end
+end
+
+---@param duration number|nil
+function Timer:start( duration )
+    self.paused = false
+    if duration ~= nil then
+        self.duration = duration
+    end
+    self.time = self.duration
+end
+
+---@param emit boolean
+function Timer:stop( emit )
+    self.paused = true
+    self.time = 0
+    if emit then
+        self.timeout( self.data )
+    end
+end
+
+function Timer:elapsed()
+    return self.duration - self.time
+end