Sorry for the delay in responding, I have been trying to get time to test a couple of things.
The inlay in the picture was done with two different tool paths. The first one (female) was cut from an outline of the shape I wanted. The second one (male) was cut from a copy of the outline however, it was flipped over to reverse the outline.
The trick is in the cutting depths. - I used a 60 degree engraving bit, I cut the female to a depth of -3 mm from the stock top.
I cut the male with a stock top offset of -3mm then cut it to a depth of -6mm from the stock top.
This gave an inlay (male) that fit in the female without much manual clean up.
The problem I had with this technique is for some reason, the engrave path is not faithful for the female part. If you look where the seahorse’s fin is, the female did not cut the angle on one side. I worked with Fusion 360 to try to correct this but couldn’t find a solution that would follow the outline correctly.
I thought I would try a different cutting strategy, I used a 2D contour and offset the male part to fit the female. - I can confirm that this is NOT the way to go. There is just too much work to clean up the parts. I haven’t finished the glue up yet but when I do, I will post a picture of the inlay, I don’t think it’s even close to the first one.
My plan now is to try and establish why the engrave tool path is not faithfully following the outline that I have. I will try a different outline to see if that helps. I created that outline from a picture on the Net so I am not sure if there is something wrong in that creation. I may try creating an outline from scratch.
I will update here once I have some news.