You didn't specify which properties you were talking about. Color is a property which can be incorporated into materials, for example. If you want to be pedantic, you're going to have to be pedantic all the time. Otherwise you're just a goalpost-mover.

It happened to a friend of a very close friend, who many hours in acrobatics, taking off in weather which was not apparently of that kind. But I notice that you, and the idiot next to you, and some moderator all felt very strongly that they know better despite the fact that it does in fact happen.

Also, there will be idiots.

There are already printers which can incorporate multiple materials into a single design. A logical extension of this idea might be a print bed which can be shipped between machines. Anyone thinking of applying for a patent might note that I have already thought that you might want it to actually be an enclosed, insulated case for the purposes of maintaining print area temperature :p

Is there really and truly any reason why a user can't reasonably expect to sketchup (or use some other similarly simple modeling program) a toy with a line drawn through it in a couple of places marked "axle" and expect software to figure out how thick that axle needs to be, and how a 3d printer is going to lay down some bearings around it while printing the toy truck or duck or whatever with wheels on it? Software can already handle turning the "solid" parts of solids into structured voids to save material and mass, I don't think it's that much of a stretch.

Most people's 3d printer needs, however, would be solved by an app which lets them drop both broken pieces of something on a flatbed scanner a few times (some of them have infinite depth-of-field per element) or use an automated turntable scanner, and then match them up even semi-manually before being able to print a replacement.

Seems to me like the best way to handle this in the short term is for hardware stores to provide 3d printing services. You bring them both pieces and they have the fancy expensive scanner and software to replicate your part, and the fancy expensive printer to print it without massive steps all over it.

No, it would not be worthwhile, unless you were using them mostly for their GPUs. The RPi CPU is not super-slow, but it's not really competitive. And you'd need to come up with all the glue logic.

Cars are frankly not all that much simpler than airplanes. It's just that the energy expended is so very much less when the relative masses are compared. An airplane has a high-output engine and is made out of sheet Aluminum, glue and rivets. A car usually has a mediocre-output engine and is made out of much sterner stuff than an airplane.

What I notice is that the technology that goes into making a better racing tire makes its way down to a street tire in a basically timely fashion, but the technology that goes into making a better interface between the plane and the air doesn't seem to make it into civilian air very rapidly at all. Shouldn't private planes have winglets and computer assistance and so on by now?

Physics cares very much what kind of safety features you have in your vehicle if it permits you to utilize physics to not have the collision in the first place, or to absorb more of that energy before any of it reaches the driver.

Yes, just as big boys wear big boy pants, big boys need to drive big boy cars. I'm retiring my W126 300SD and moving into a D2 A8, from one full-size car to the next. Even into a big-bodied one. It's actually 400lb heavier, in spite of being all-Al, but it's around 600lb lighter than my car's successor while still having inspiring collision resistance. It has a fairly broad collection of airbags while my benzo has zero. There's full-size cars around, they just cost more. But then, my clothes need to be in tall sizes, or my shirts show my belly and my pants fall down. I have to pay more for those. I'm not surprised to pay more for cars as well.

Not all of Musk's ideas are as brilliant as Tesla or SpaceX. PayPal is shockingly bad, and only popular because eBay forces you to use it and excludes everything else.

One of the benefits of cars is that they seldom get picked up by a sudden gust, flipped over, and slammed into the ground during takeoff, killing the pilot and passenger. Mostly because they don't have a takeoff phase.

The Audi A8 was offered with a warm weather package, the sunroof goes from ordinary metal to carrying a solar panel which is used to run the fresh air blower while it's parked in the sun. Came out in 1994. Doesn't charge the battery though, which is unfortunate given how much electrical crap is in there.

But having lighter batteries is a plus, not a drawback, even so.

And yet, using old car batteries for grid storage is Nissan's Leaf battery recycling plan.

Won't hurt though, and it may well be a benefit.

The car batteries only keep their peak charge characteristics for the first few thousand hours, but they still keep working for a decade or two.

What? Who told you that?

Give it time. Eventually the panels will be so cheap every roof will have them, even the less than optimal ones.

Nissan offers a "whole house UPS" feature for its Leaf EV in Japan. In the event of a power failure your car can run important appliances like the fridge for a few days. You can use it to reduce your energy bills by storing solar energy not used during the day too.

So where do you park? If you have any off-road parking then a charging point can be added fairly cheaply. If you park on the road then you might have to wait a few years for road-side charging points to start appearing.

Your issue is exactly the same one that early buyers of petrol cars had. You need infrastructure that isn't available yet.