Not knowing all the geometric names by hard, it took me a while before seeing that this form is actually a dodecahedron. The triangles that form the tetrahedrons have some indents, but if you look closer, those indents are made out of the lines of the smaller isosceles triangle and those lines keep going further to the bigger triangle. The two outer outer lines of the two isosceles triangles are connected by a line in a right angle from the smaller one.
I wouldn't have figured out each angle and ratio of sizes without the 3D modeling app uMake. These past months I have been learning 3D modeling using this app and slowly it's becoming one of my favorite tools to design and sketch sculptures in 3D.
Here you can see my preparations and one of the 3D model from my upcoming project Acoustics Based on Jamnitzer. Next month I will be ordering the material, but for now I’m still finishing the last 3D models and contemplating whether I will create them in aluminium or cortensteel.