So I finally got tired of resting my arm on the hard plastic, especially after it started going numb while I commuted to work for 1.5 hours every morning.
I didn't really like any of the offerings for armrests out there, because to have a drink in the cupholder in one of them means leaving the armrest flipped open. The other slides forward with this awkward reverse rake. Some even take up the cupholder space. Despite the fact that the cupholder location in this vehicle is terrible (I think porsches have it right, though the worst I've had so far is the S2000), I tried to think of a way to cover the box, and also retain cupholder accessibility when needed.
Total cost of parts: $20
Time: 1.5 hours
Tools: Band saw, hacksaw, screwdrivers, glue, sandpaper/file, staple gun, sharpie.
Here's a picture of the result, which hasn't been mounted yet because I ran out of daylight. It is kind of hard to explain in one picture, so I'll show three:
So it basically has two hinges, and can hinge open like a normal armrest (from the back), or it can fold completely back and cover the spot where the rear seat armrest would be, and completely clear the entire center console box (including the cupholders). Hopefully that makes sense.
I wasn't originally going to create a DIY but I figured I would because I... would. The result is I don't have any pictures of the first steps. Not that hard.
Here is a picture of the dimensions I used:

I purposely made it symmetrical because I think it looks better. Especially when folded back, but feel free to modify it.
I used a piece of pine plywood I had lying around, cut to those dimensions using a band saw, and then used a metal file to file all the edges round. I also filed the front trapezoidal area of the armrest significantly more, so it raked downward toward the edges. I also filed the front underside edge, to make a spot where your fingers can easily grab the edge of the lid.
After cutting out the piece of plywood, I used some high density foam I got at JoAnn's, and black vinyl. I cut the foam (green stuff) into a shape a slightly bigger than the wood, and shaved off some thickness in the trapezoidal area (on the side touching the wood, so you don't get an uneven texture against the vinyl), again so I get that downward rake in the front. I then pulled all the sides of the vinyl over, and stapled it down.
Here is the first picture I decided to take:
Okay so we have the armrest. I used some hinges I got at Lowe's. I also found a metal plate/bar. It doesn't really matter what you use.
It is important to mount the hinges in the orientation I have them, because these only close completely in 1 direction. If you mess with a hinge you'll understand, typically they can only close like this ">" but you can't flip it around the other way, it will only close to a shape like "L"
First the plate: I measured it to about 8" long because my armrest was 16.5" inches long. I cut it by hand using a hack saw because the neighbor came over and yelled at me for using a band saw so late. Justifiable reason I suppose.
Second, the hinges. Important part here, as you need to place the hinge that goes on the armrest in a very specific place. For me, since I cut the plate first, I knew exactly where it was supposed to go. Pretty much 8" from the rear edge of the armrest. Enough so the armrest can open up normally without the rear hitting the console. This also means, when "flipped" the armrest sticks out half an inch further (8+8 = 16, 16.5-16 = .5) which is fine because I kind of want it to cover the console-mounted hinge anyways.
Okay so I had some adhesive lying around that works really well for metal-on-metal stuff. I suppose you could use epoxy or superglue. The alternative is bolting it all together and putting counter-sunk holes in the armrest so it will lay flat. I stuck with glue for now, and those hinges are really stuck to that metal plate. You build it so it looks like this:
Now you'll notice the bottom looks all ugly.
First i glued all the fabric down so it wouldn't cause wrinkles. Then i threw a ton more staples at it because... I can.
Then you cut out a piece of vinyl like this:

And use a sharpie on the white edges like this:

Then glue it down using something like this:

And then I stapled it around the edges like this:

because the adhesive wasn't holding and it was the underside anyways. I used a sharpie on the staples, it is more purple in the picture because of the flash. I really don't think you'll notice in the car.

Now the large metal bar will be scuffed and painted, probably plastidipped black. I just haven't done it yet. I'm thinking I'll fill the holes in the plate with bondo or whatever, have to find something in the garage.
My original intention, use a bunch of kitchen door magnets on the underside of the armrest so it "sticks" to the metal plate, allowing you to open the armrest using the hinge that will be bolted to the center console. Like a normal armrest.
So this:

Would be stuck like that from magnets on the underside of that plate. Unfortunately the great kitchen magnet purge of the decade happened not too long ago, so I have no magnets. I will get some soon.
Here's what I want to accomplish, with a neat paper demo cupholder to boot:

(this one could also just open without propping it up)
And now in the car:
Mounting point in the vehicle:
Yes this will require me to drill holes in the center console. I will be putting a reinforcement plate on the other side, using two countersunk bolts that go through the hinge, console plastic, inner plate, then one of those anti-loosening rings that I can't remember the name of right now, and a nut. I'll also be putting some felt between the metal hinge and console plastic because... scratches.
I've also got some little rubber feet that I'll be putting on the edges of the armrest that come in contact with any plastic.
I have not mounted this in the car yet because I ran out of daylight, and out of time. I'll hopefully have this done in the next few days/week. I've seen pictures of the console there when removed and I don't foresee any issues.
This write up took longer to write than actually doing it.
Comments, hatred, and gushing adoration can now commence.