Here is a nice simple but sturdy way to fit a light to your Uni - when the nights draw in or for riding at night.
Allows adjustment in both up/down and rotation.
No real tools as such - snips to cut the cable tie - saw to cut the tube if you do not have an off cut laying around - a file to put a semi circle shaped cut out in the back of the pipe.
Step 1: Gather
1 - cycle light with standard clamp
1 - piece of tube - thin walled and about the same size as your seat post - length should be just short enough to let ya put the light on and off the bracket (if removable) - on a small note, do not make the tube too long or you will bust your light if you dump your uni.
1 - cable tie.
Step 2: Tube
Take your length of tube and file a semi circle in one end - not all the way to the edge as this will leave a small space for the cable tie to exit when fitting
Step 3: Assemble
So - take your cable tie - pass it round the seat post - through the tube - through the clamp - back through the tube - back round the seat post and zip together to give a good tight fit but with just enough give to allow you to move the light up/down as needed. Cut off extra material.
Step 4: Let There Be Light
Off ya go - never more restricted to the daylight hours. Riding when it is dark is harder that you think, challenging though.