Making Rulers.. and rocketry tools!

Yes.. I've been making rulers! It started because I wanted to make a tool to give away as a freebie at an upcoming Rocket Design Workshop I'm running for North Wales Tech group. One of the challenges when building small rockets is marking straight parallel lines onto the body tubes to mark fin positions or other attachments. A solution is to use a piece of angled bar as it will always lie accurately along a tube and cannot be off square. So for the workshop I thought it might be nice to knock up a small laser cut keepsake one complete with ruler markings and we'll put the workshop date and logos on etc. The two circle symbols on this one are used in rocketry to represent the centre of pressure and the centre of gravity which we'll be discussing in the workshop too so they act as a nice reminder. I cut these on the laser cutter at my nearby newly established Pontio fablab, which is excellent and its so easy to get good quick results on a laser cutter. However I can only access the space every now and again and wanted to see if I could make some rulers without a laser cutter on my cnc router. It's trickier.. the 2 small key chain rulers here are made on 3mm ply and have been engraved with a fine V bit, they are ok, but its difficult to get the resolution and clean cuts at this scale... I obviously need a laser cutter at home... feel free to send me one if you have one spare! Finally someone asked if I drew all the lines of the ruler sections by hand... there is a brilliant path effect in the mighty inkscape which allows you to create a scale along any shaped path.. brilliant!