Most of the modern keys I've seen are very narrow.
The mk2 keye is quite wide in comparison.
I recon it is possible, but won't be a straight forward job to do.
I recon a better fob than the plastic one is the answer.
I did make a carbon fibre one a few years back.
Looked OK, but as it was wet lay and I didn't use enough fibre in it. It wasn't very strong and is starting to delaminate.
I recon an aluminium copy of the original fob design would be awesome.
Jason.
*edit..
Found this . You might find useful..
http://forums.vwvortex.com/showthread.p ... &_k=zo1x30