In creating inlaid marquetry, one of my great discoveries was a precision router base for my Dremel tool, by Stewart MacDonald. The accuracy for routing small details can be achieved to within a few thousandths of an inch (.001″).
By first scoring the edge of the marquetry picture into solid wood with a scalpel, then setting the depth of the router bit to .021″, the pattern can be accurately routed using a 1/64″ cutting bit. The marquetry piece is then inlaid and glued in. Once the tape is removed, the inlay will be about .004″ proud of the wood, and light sanding will level it to be perfectly flush.
The result is perfectly inlaid marquetry. The right tools make a difference!