One of my first keychain experiments a while back. The process involved in this little guy entailed designing an inner laser engraved piece that would be cut out. Then Taking the svg that was used to create the cut, you extrude and create the 3 dimensional cage around it that the engraving will sit inside of! To make sure the wood engraving is nice and snug inside the 3d print, a little playing around is required. You have to know your 3d printers tolerances very well. Identify the height at which your engraving sits perfectly within the 3d print after printing the bottom half. Once you think you have a snug fit, you enter a filament change into the gcode at that height. This makes the printer stop in the middle of the 3d print so you can put the engraving inside! Then press start on the print again, and the 3d printer encases the entire engraving within the cage, no glue, no snap fit pieces required! 

These are cool to make... I got the process down pretty decently so I might honestly do a small run of this kind of thing at some point!