Hi,
There seems to be quite a few threads on DIY when doing a Google, although some are quite old and results do not always seem to be that good or worth the time and effort. I only found ones using speaker cones and perhaps it would be more fruitful to use the Aurasound type transducers instead.
Anyway heres some threads I saw:
DIY tactile Transducer Another
probably the same ones you found
I would be interested in hearing about any DIY attempts, even if its just for a laughs and fun

. Be prepared....!You have get used to a bit of ribbing when talking here about this subject
Have you some clever techy ideas in mind or just plan on using modified speaker cone(s)?
Here's
The thread I think Moonfly was refering to, if you're interested there are a few more lying around here somewhere.