Step 11: Make a Base for the Coils
I made my prototype out of foam core, but this will depend a lot on the size of your coils, the size of your magnets and the shape of the frame. Plus, if you're planning on keeping this outside instead of hooked up to an AC vent of whatever, keep weather proofing in mind (and while you're at it, give the Pringles can a good going over with Scotch Gard--I haven't tried it, but let me know what works for outdoor versions you make).
The most important thing is to try to get the coils to be as close to the magnets without collisions. If you can position the coils on the base so they sit just 1 mm below the spinning magnets (watch out for wobble) then you're in good shape. Also, try to make the base as stable as possible. At higher RPMs, the turbine can really start to rattle a bit, so keeping things together in those conditions is crucial.