Very nice, David! That's quite an elaborate process to create those tiles. Thanks for posting, and be sure to show us the finished result whenever you get back to that one
As to the original post, what about building up the log out of small sticks like normal, and then using a long drill bit on a drill press to make a hole through it the long way, and then shove a dowel through it?
You could also brute-force it by drilling and inlaying dots one at a time in the finished rosette, but that would of course take longer and be less identical on each tile. It could also be interesting to do it like that, but without trying to make it repeat with the tiles... make a different pattern out of the dots on top of the mosaic. Or even do something like my rosette style, building a more elaborate non-repeating image, but with a mosaic background instead of solid wood. I think I'll have to try that sometime.
Attachment:
Rosette.jpg
And here's a photo album that I ran across that has some great marquetry rosettes, including some in-process shots of one like that Arias rosette David posted. http://www.flickr.com/photos/rigoletto/
Looks like he does it using a wood strip bent into a squiggly line, semi-circles that match the bend radius on the squiggle, and putty or sawdust/glue mix to fill the rest of the space.
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