I’m not exactly the best modeller in the world, and I still suck at unity scripting, but I still think this is pretty good demo, so go ahead and give it a try :) Print this marker sheet beforehand.
Behind the scenes.
What I did here was using FLARSquare‘s line property for steering wheel rotation in flash, reading it through ExternalInterface callbacks every 100 milliseconds in html and notifying unity via SendMessage(). Not a rocket science, but there are few tricks to learn from it; for example, inobvious benefits of using multiple co-oriented instances of single marker:
Thanks to this, user has enough motion freedom to maintain control over steering wheel without visual feedback (webcam video) and, therefore, can focus on unity experience better. For another example, FLARToolKit is now not compiled together with controlled content and you can easily replace it with something else, thus taking it out of GPL2 sec 2b reach and limiting it to controller SWF sources only (note that ARToolworks lawers may be thinking otherwise).