I have found a source for the very small green visco fuse:
http://www.skylighter.com1mm Cross-Match Visco, item # GN1010This is the small diameter fuse like I described above. I emailed the company to verify this before posting.
But (there's always a but), there are a couple of things that should be mentioned.
First, at $13.63 (plus shipping) for 50' this fuse costs about twice as much I usually pay for the standard visco sizes.
Second, Skylighter has a $30 minimum order. Unless you are ordering other items, you would have to buy three rolls of this fuse to meet the minimum.
All that said, this is the
ONLY place that I found that sells this fuse after lots of web searching.
If micro is your game, and you want to use the smallest visco available, then this is it.