I have been watching Frieren: Beyond Journey's End and I saw so many different variety of weapons and staffs that I saw them as being good practise for me to get better at using CAD software.
I used Shapr3D to make the CAD file. To model Stark's axe, I went through the anime until I found various frames where the weapon was in frame. I proceeded to find a middle line of the axe and shaped one side of the axe handle. Using the revovle tool, I was able to make a good handle and a symmetrical central section of the axe. I proceeded to draw around the axe heads using various line tools.
Due to the axe's massive size, I had to print it in multiple parts. I printed part of the handle using Bambu Labs Black Walnut PLA Wood. All parts that looks like steel were printed out of eSun PLA+ Silver filament and central part of the axe was printed out of Bambu Labs Black Basic PLA.
All handle parts were connected by various screws. The axe head parts interlocked together through dove-tail joints and joined to the central part by some push pins.
I used an aluminium rod in the middle to support the structure.
Funnily, while having some swings of the axe, I have broken it twice XD the screws used to connect the handle have snapped because I over tightened it when they would unscrew themselves XD and I also knocked the axe head on my axe and the dove tail joint snapped XD
To fix the axe, I did use a heat gun used for circuit boards because the heat gun has a more narrow corridor of heat. The downside to using the heatgun is that the plastics surface finish is affected and stands out from the 3D printed section.