Some concepts in this video have been pictured in a somewhat simplified manner to make it more accessible to a less specialized audience.

Contents:
00:00 General intro
00:56 Conic constant explained
10:00 Explanation of the manufacturing process
12:25 Testing the mirror
15:32 interferometric evaluation using DFTfringe

Additional info on clips/subjects featured in this video (in the order of appearance):

The fire clips were taken from the news site regio14.nl:    • Enorme vlammenzee bij autobrand 🚒 🔥  

The short clip of (Ralph) grinding a telescope mirror is taken from:    • 20121027123510 1  

The "mirror test" for animals actually has little to do with optics: https://en.wikipedia.org/wiki/Mirror_...

If you want a more detailed story on conics: https://www.telescope-optics.net/coni.... Telescope-optics.net is a great source for theory on optics.

Clip of making the ellipse using a rope demonstrating constant path length is taken from the following video:    • Ellipse (string and optical properties)  

Astroforum link to 610mm flex mirror by forum user Firstlight (in Dutch): https://www.astroforum.nl/forum/instr...

Document with a description of how to making a "Ceravolo" type interferometer yourslf: http://www.ceravolo.com/Interferometr...

Links to DFTfringe software:
interferometry groups: https://groups.io/g/Interferometry. In this community Dale Eason answers all the questions on technical subjects about the software.
Download the latest version of DFTfringe here: https://github.com/githubdoe/DFTFring...
DFTfringe walk through, displaying most of the basic functionality:
   • DFTFringe quick start guide version 2...  

With the interferometric tests I considered astigmatism in the mirror and only left the following zernike coefficients unticked:
Piston X-tilt, Ytilt, Defocus, Xcoma, Ycoma.