Here's how they cast an 8m class mirror at the University of Arizona. This is for the Giant Magellan Telescope, not the VRO, but it also did that one. \
lulz. Easy. Okay. It might be the easiest part of this build (I have my doubts to the accuracy of that), but let's not get carried away with slinging words like "easy" around things that are measured to microns accuracy and took years to build.
Maybe not “easy” but it was straightforward in comparison to much of the other things on the project. It was done in the U of A mirror lab and it’s a pretty well-defined process to build these mirrors, with a small exception for this mirror being that it’s a combination M1/M3 with two different grinds, but it’s about as close to a factory process as you can get for this project. Before the mirror lab, Corning would often build the big mirrors, both for science and defense.
The 300T telescope movement assembly which can move the 300+ Ton telescope 3.5 degrees in 5 seconds, and the 3.2 GP camera especially are quite a bit harder to build, engineer, and integrate.
