For more information see:
Truncated Triangular Trapezohedron: Dürer's Solid
Mathworld: Dürer's Solid
As the above articles suggest, there is some disagreement around the exact form that Dürer's Solid takes, with a general agreement that the acute angle of the rhomboid face is between 72° and 82°.
For me, however, the solid so defined lacks some elegance. My version of Dürer's Solid uses an angle of 60°, and results in a shape made of equilateral triangles. The contrast between the two solids is most easily seen when the 'flat pack' versions are compared.
I acknowledge that the 60° version does not match the object in 'Melencolia I' very well, but I think it's a 'purer' object. I wonder what Dürer would think of it?
Use Customizer to scale your version to the size you'd like.
For comparison, see my Dürer's Solid (72°)