From post #11 ...

Anything to improve visibility. Reflective paint, glow in the dark paint, ways to mount lights to pedals, crank arms, wheel spokes to combine motion and light to help attract the attention of drives.

I don't know of the modern bicycle that does not have a reflective logo, reflective stripes, pedal reflectors, spoke reflectors, etc. Look at a bicycle ... where else would you put reflective or even active lighting? The rider is the most prominent part of a bicycle/rider configuration and the savvy rider has a helmet with passive and active lighting, a hi-viz upper vestment, leg stripes and most cycling footwear will have passive reflection. It's enough.

Way to make a loud noise. Air horn/motorcycle horn of at least 110 db. Though to be honest, the louder the better.

If you needed a loud noise to keep from being smished and it worked then you weren't in any danger of being smished. Loud sounds are a reaction. In most deadly scenarios it's already too late by then. That's why in my state an overtaking vehicle is supposed to sound their horn to announce their presence. Most don't. Good. Because I already knew they were there. But I get it. The active element in a potential collision has most of the control over the outcome. I don't need or use the horns in cars, and I have never used bells or horns on bicycles. Except for friendly signalling.

Flag: Ability to easily attach and remove from the bicycle. A blinky light of at least 350 lumens at the top would be ideal.

Recumbent bicycles and especially low slung racing style recumbent tricycles that are being operated on public roads can benefit from 6' flags, but a standard bicycle absolutely does not need one! If a rider cannot be seen without a flag the addition of a flag is not going to improve the situation enough to be worth the hassle of its impact on handling, wieldiness, etc. A flashing light on top is just more passive annoyance. What I am trying to convey by this post is that bicycle riders must stop thinking that passive strategies are effective. If a car is on a collision course with you, you must somehow get out of its way! You must not rely on them to make you safe. They may not. Then what?

8. What should a car driver do when they see a cyclist in the street?
The most important thing is to maintain at least three feet of clearance from the cyclist at all times. A pothole or bit of road debris that even a small car would never notice with modern suspension can send a cyclist head over heels.
3' is not a magic number. If a car slides past me with 12" clearance, going just 5 or 10 mph more than my speed, I am not bothered. If they blast past, 3' away at 45mph I AM bothered. It was wrong of the DOT to pick this magic 3' distance and then give drivers the license to pass bikes at 45, 50 and much more miles per hour! If you fall towards a car that is 3' away it will hit you in the head killing you instantly. If that car is going less than 20mph relative to your speed you have a chance of surviving. Relative speed is the metric that should have been used when governing motorist behavior when overtaking bicycles.

Second, I really wish someone would look at body armor options. There is a lot of seemingly good body armor for motorcycle and car racers, but the expense is crazy and the fitment requirements seem difficult to meet unless on is very knowledgeable or is buying local with some very good customer service. To be honest, an inch of padding on the sides of the knees and sides of the hips could be the thing that saves the cyclist a couple of years of physical therapy after even a low speed interaction with a car driver.

Motorcycles move the rider through the air fast enough that wearing padded clothing doesn't overheat them. But it does overheat many. I have a lot of tolerance for heat but most of my friends ride practically naked. Down to sandals, because cycling shoes are too hot. Now you want to put armor on cyclists? Don't get hit. Rule number one. If you are hit there isn't any armor made that can save you. Just accept that and adjust riding style to suit. It might mean MOVING to another city or state if the driving culture where you live is so awful that you need to consider body armor for vehicular cycling.