He claims that this "firmament" may have been recreated in the lab by spinning hydrogen atoms in a centrifuge. It's a pinkish lens but getting it to hold together wouldn't be an easy matter. Besides, if the sun is going red giant the heat will eventually become too hot for any type of reflector or lens. Christians don't worry about it because they have been told beforehand that neither the earth, nor man, will need the sun, or an orbit around it, when Christ returns.
You are correct in noting that there would be attrition, but this can be resolved by simply continuing the program under the assumption that losses would occur.
We could even find ourselves in the position of the Dutch, or those in New Orleans, having to continually build up the barriers to prevent our destruction. But there is a difference. They could leave -- we can't, unless we simply move outward to the next planet.
I'm not ready to abandon Earth quite yet.
Sunglasses? -- Okay, but that would be an even larger undertaking than mirrors or solar cells. There are only two locations where items can be placed to interrupt light from the Sun to Earth. One is an orbit inferior to Earth, such as occupied by Venus. Since objects, or gas-clouds, would orbit at a different speed than we do, we would have to fill that orbit with gas in order to protect Earth. It would take a lot of material, more than our planet alone could provide. I'm not saying it's impossible, just difficult.
Perhaps it's not the right way to go. I like to accomplish more than one goal at a time. Solar cells do that. Even mirrors could be combined with solar cells to do double duty.
The other location is a balance point between the gravitational attraction of the Earth, and the Sun. Called a LaGrange point, it is moderately unstable, but could be maintained as a place to develop energy, and shade Earth at the same time.
Such a structure would have to be enormous to be even minimally effective, but it could be even less than paper-thin. Calculations can easily be done to determine how much material is required. Spread thin, it is not a prohibitive amount. Much of it could come from the Moon. Robot factories could launch material from the Moon without using rocket fuel. They would do it with electromagnetic catapults. (First you have to get to the Moon, of course.)
I also like mirrors for terraforming places for colonization, such as Mars. Mars needs to be made warmer, and mirrors could easily help to accomplish that.
I enjoy the vision provided by Biblical interpretations, but I do not believe that the Bible and Science are in conflict in these matters.
Eventually, it is true that the Earth will be destroyed. By that time, we will be gone, or very, very different. If we continue with our scientific pursuits, modifying the solar system, or other star systems, may not seem so outlandish.
And trust me, we won't have to leave a forwarding address in order for Christ to find us.