So to update, I created the grilles right after work out of 1/4" MDF
I made these beauties with a jigsaw, and a holesaw and some CAREFUL eyeballing. haha.

Here's maybe a better shot of just how small this part is

Shot them with black paint

This was tedious right here... I used my upholstery glue and just sprayed it into a paper plate, then used a tiny foam applicator pad (the ones I usually use to detail a car's tiny little crevices like a door jamb) and rubbed the glue only on the sides of the shape. I let it sit a little while to tack up, and then placed the grille cloth on in a tight fashion. The tricky part was keeping the glue off the face!

Forgive the weak pics here, it was late and my camera phone shots are just awful.



Now, I'm going to go over all the bad stuff that happened. Ok, so as you can probably tell the pillars are pretty much out of the way and done. I'm 95% happy with them, and for my first ones ever, I can definitely live with the result. Let me share with you some of the pitfalls in my design, so if you're following along you'll make less mistakes than I did (or new ones, but that's cool 'cause we learn.)
1st mistake, and it was a biggie, do not use Melamine wrap around your shape (the white strip stuff I used to make the lip edge of each of these) if you can help it. The material has a few undesirable traits and one just bit me in the butt this afternoon. There's this adhesive that is heat-activated, on the backside of this material. Well, the Vegas afternoon sun beat down on my car, and partially lifted the vinyl where it attaches to this Melamine strip. I can tell it is this adhesive lifting, because under the vinyl it is ultra-sticky but the adhesive from the Melamine strip is stuck to the vinyl, and not stuck to the Melamine! So, the right product to use is something else, like a piece of thicker laminate without the glue perhaps. Pros use low-temp plastic, cut with a saw from sheets into strips. They take a heat gun and bend it slowly around the shape intended, and air-staple it as they go. The plastic holds a shape better (which gets to my next issue with the Melamine strip in a minute), and will work in deeper lip shapes or any thickness you need, because you cut it to fit. This would be great if you can find some, and next time I build some of these, I'll absolutely search harder for it.
2nd problem with the Melamine, is that it bends. There's this slight bowing in my shape on the straight lines that make up the "teardop" type form. This was noticeable when I built my grilles, because that shape was the original stencil exactly and it had no bow on the straight lines. End result, the grille looks ever so slightly less exactly like the shape it is meant to match with. Now, I may end up making two more grilles, with this exact bow shape built in to it to get it "just right". I'm not really sure yet.
Another major mistake was the over-application of Bondo on the first round. In truth, you should never use more than golf ball's size of filler at a time, in most situations. I just got rushed and it was a huge time-killer. The other applications were tiny and worked flawlessly.
At some point, before I started this whole thing with these pillars, I should have found a plastic sealer product of some sort that helps attach the primer to the plastic. In some places (not visible wrapped in vinyl but I know it happened so it bothers me), the high-build primer came right off, after I hit it with the upholstery spray glue. It was a darn mess, because the primer stuck like crazy to the glue as expected, but the plastic and the primer separated as if they were never really together. I cleaned the plastic pillars aggressively with isopropyl alcohol, sanded and "keyed" the pillar, and then cleaned it again...but it didn't work. I would have tried acetone but I wasn't certain the acetone and the plastic would be happy together. I should have tried to find a plastic sealing / etching product that locked into the plastic and created an initial biting layer for the primer underneath. The Bondo Gold filler had some of this same problem in some areas, but not anywhere in the critical area of the bond I made, or its final shape.
I wish I would have made the pillar shape a little larger, for a bigger midrange down the road some day. There's a GR-Research speaker I saw recently, and I REALLY want to try it sometime. Well, it ain't gonna fit these pillars, that's for sure. This is more of a compromise thing and a future-planning thing you have to think about, when you build. I didn't want to kill my vision in the corners of the pillars, in case some kid runs out in the street corner or something, and then suddenly because of the pillars I built, I couldn't see. That would be a really bad thing, somewhat like getting rearended because your tail lights are blacked out. It is a mod and you did it, and now someone gets hurt, etc etc. That might be extreme and pointless to consider, but it was on my mind and effected my build's plans.
I just barely over-stretched the vinyl on the passenger side. I actually think a few more days of baking heat will pull the stretches out, but it is annoying. The driver's side which was the first one, really just fell together and the vinyl laid down perfectly, with minor tugging and then lots of folding and cutting. Well, the passenger side, it just didn't have the same ease in laying down and wanted to stretch like crazy all over the shape. End result, there's tiny stress stretches at the very bottom of the shape, and apparently I'm the only one that can see them in my family but I bet you guys with eagle eyes see them in the passenger one. Vinyl can be a really tough product to work with, and it never really lays down 100% completely flat, so be sure to use a good vinyl and use one with a nice aggressive texture, to hide the natural imperfections that come from using it. As you can tell, the vinyl I chose is a 100% perfect match to the charcoal interior panels. This definitely helps!
Oh yes, I made another critical mistake and that was cutting the pillar's little internal piece of material that rests inside with the speakers. That is high-pile carpet and to get the shape exactly right, I actually cut it INSIDE the pillar. I glued it in, and had to use an exacto knife to cut out the excess carpet. BAD idea. I must have been really tired when I thought this up, because...well the knife cut the vinyl too. None of the cuts are outside of the pillar pod's little lip, but on the lip itself there's many little tiny slices. I had tried to keep the knife far down in the pod lip, but it must have tracked up a few times and made some damage. Luckily the speaker grilles completely hide this, but again... I KNOW it is there. If I were doing this again, I'd just take the shape very similar to the grilles I made, and just cut it exactly and place it in.
So, despite all the little boo-boos and learning mistakes, they sound fantastic and meet design goal criteria in all other ways. I am definitely happy with the result and my next pillars will be that much better from the lessons learned by the mistakes I made.
Remember that factory pillars run about $80 or so, unless you can score them cheaper somehow. There's no substitute for this type of custom work, if you want your vocals and high frequency instruments up on the dash and able to present a rock-solid sound stage, so it really is up to you as to how much you want quality sound. Gotta get through it to get to it! Or hire someone like me to get through it for you. HA! If anybody wanted something like this, I'd do it but I'd demand a grip of money for the time and frustration. These were definitely a 10 out of 10 in difficulty level for me, and compare something like that wood speaker box with the many angled cuts in it that I did for Stefan's (Reidster's) build, that would be like 3 or 4 our of 10 in difficulty. So this is nuts.
Well, the center channel is next. Here's a teaser shot.