This is a tremendous scale job that I undertook to get myself a 3D printable Gjallahorn! All parts slot/paste and fit together to create this replica and are printed. It's opening casing door with pivoting housing and casing.
That is a slideshow of the best way to put this beast get printing your own!
Print all the bigger parts at 0.2mm layer height and 5% infill. I 'd push up the infill to 15% for the parts that are really little.
Have a look at the construction directions on the best way to put it together