The original intention of this design was to be somewhat useable and 3d printed: PETG handle and dowel and PACF head with 5.5mm (diameter) carbon fiber rods running the length of the handle for structural support. Seeing as the intricate dowel (if it can even be called a dowel) intersecting with the CF rod holes creates an impossible overhang situation, I've since scrapped the project. I do still like the general design though and have added the .STEP files for anyone who is interested in making it a reality.
Model units: mm
For anyone wanting to make this a display piece, I would suggest removing the holes and simplifying the dowel to a traditional dowel, and printing the axe in the 3 separate pieces as it is currently separated.