diff --git a/udp-test-send.py b/udp-test-send.py
index 63db20a..216d589 100644
--- a/udp-test-send.py
+++ b/udp-test-send.py
@@ -1,5 +1,7 @@
 import socket
 import time
+import argparse
+import math
 
 UDP_IP = "192.168.100.1"
 UDP_PORT = 3663
@@ -9,20 +11,72 @@
 ON = bytearray(255 for i in range(MAX_LED*3))
 sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
 
-def chase(r=255, g=255, b=255, sleep = 0.01):
-	for i in range(0, MAX_LED):
-		output = bytearray(0 for i in range(MAX_LED*3))
-		col = (r << 16) + (g << 8) + (b)
-		output[i*3:(i*3)+6] = col.to_bytes(6,byteorder='big')
-		sock.sendto(output, (UDP_IP, UDP_PORT))
-		time.sleep(sleep)
-	sock.sendto(OFF, (UDP_IP, UDP_PORT))
-	
-def rainbow(sleep = 0.2):
-	pass
-
-while True:
-	sock.sendto(ON, (UDP_IP, UDP_PORT))
-	time.sleep(1)
-	sock.sendto(OFF, (UDP_IP, UDP_PORT))
-	time.sleep(1)
\ No newline at end of file
+
+def flash(sleep=1):
+    sock.sendto(ON, (UDP_IP, UDP_PORT))
+    time.sleep(sleep)
+    sock.sendto(OFF, (UDP_IP, UDP_PORT))
+    time.sleep(sleep)
+
+
+def chase(r=255, g=255, b=255, sleep=0.01):
+    """Chase a single colour around the dome in order"""
+    output = bytearray(0 for i in range(MAX_LED*3))
+    for i in range(0, MAX_LED):
+        output[i * 3] = r
+        output[i * 3 + 1] = g
+        output[i * 3 + 2] = b
+
+        sock.sendto(output, (UDP_IP, UDP_PORT))
+        time.sleep(sleep)
+
+    sock.sendto(OFF, (UDP_IP, UDP_PORT))
+    time.sleep(sleep)
+
+
+def rainbow(sleep=0.05):
+    """Construct a sort-of sinusoidal wave pattern"""
+    wave_hz = 1
+    r_offset = 0
+    g_offset = 2 * math.pi / 3
+    b_offset = 4 * math.pi / 3
+
+    colours = bytearray(0 for i in range(MAX_LED * 3))
+
+    dome_time = 0
+
+    while True:
+        dome_time += sleep
+        for i in range(0, MAX_LED):
+            relativeTime = dome_time * \
+                (2 * math.pi * wave_hz) + \
+                (2 * math.pi * i / MAX_LED)
+
+            r_val = int(255 * (math.sin(relativeTime + r_offset) / 2 + 0.5))
+            g_val = int(255 * (math.sin(relativeTime + g_offset) / 2 + 0.5))
+            b_val = int(255 * (math.sin(relativeTime + b_offset) / 2 + 0.5))
+
+            colours[i * 3] = r_val
+            colours[i * 3 + 1] = g_val
+            colours[i * 3 + 2] = b_val
+
+        sock.sendto(colours, (UDP_IP, UDP_PORT))
+        time.sleep(sleep)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "mode",
+        help="Which mode should we run in? One of flash, chase, rainbow"
+    )
+
+    args = parser.parse_args()
+
+    while True:
+        if args.mode == "flash":
+            flash()
+        elif args.mode == "chase":
+            chase()
+        elif args.mode == "rainbow":
+            rainbow()