Sounds cool! I built a pair of AV-3s this summer and they turned out great. I finished them on the tops with black paint and lacquer (this took lots of sanding) and the bottom section I wrapped 24 gauge stainless steel. The steel worked like a thick veneer and looks great. I'll try to find a pic.
For dampening I used peel and stick floor tiles, doubled them up a few times and glued them to the walls where the dampening goes. I then covered all of that in 1" open foam I picked up at Hobby Lobby. It made the box dead, although (as mentioned countless times before) it probably isn't as effective as No-Rez. Either way it sounds great. I upgraded to Sonocaps too.
As for the subwoofers... yeah. The Av-3s have bass response, and it is nice, but it (to me) sounds a bit dry and thin. Most subwoofers sound this way to me, so it isn't really a knock on the AV-3. However, I built an Infinite Baffle subwoofer into the wall space behind my mains (2 x 18") and that thing is something else. Obviously you gain another dimension, even if you don't think your music needs it. Trust me, a sub will help. These aren't the LS-9s or anything.... 
Show us how it turns out!
EDIT: Here's mine:
Those look really nice. Nice job finishing those. I really like the combination of metal/paint. They look very professional. Is that sub-woofer built into yhour wall? It looks that way.
I finished constructing mine yesterday and installed all the hardware in the boxes. I have been using a pair of Bose 201 bookshelf speakers for quiet some time and I used to think they were pretty nice. Ummm.....well. I'm not sure I'll ever be able to purchase speakers at a big box electronics store again after listening to the A/V-3's. I am very pleased with the way these sound, and I'm glad I could get them at the price I did, with a bit of work of course. Compared to the Bose speakers, which are my only reference point, there is a very substantial increase in both the definition and fullness of the sound. I'm quite happy with the amount of low end these produce for only using 5 1/2" drivers. They sound very good with most music.
I did a few things in the construction of my boxes:
1. I made the front panel almost 1 1/2" thick. Even without dampening material attached it was pretty "dead" sounding.
2. Since I only had one sheet of no-rez, I used it for dampening immediately surrounding the drivers. Everywhere else I used a combination of Vinyl Composite Tile, about 1/8" thick, and 1" open cell foam. I found the foam at a craft store.
3. I built the boxes 48" tall. The floor for the speaker portion is at 42", per the plans, and I constructed another small box at the bottom with the additional 6". This small box is filled with sand. I did not want to have a base extending past the footprint of the speaker box, so I was trying to bias the weight towards the bottom. Each speaker took almost 1/2 of a 50 lb. bag of playground sand, so there is an additional 20-22 lb. weight right at the bottom. It worked out pretty well. I wouldn't trust them if I was in an active house with kids, but since it's just me, my fiance, and our dogs they will be fine. You really have to work to push them over, but once they pass a certain point there's no stopping them. They look really slick, just nice narrow boxes coming right up out of the floor.
Right now they are set up in my bedroom, waiting for me to complete my front room renovation so they can be moved to their new home. I'll wait until I"m done with that in order to veneer them. I am planning on a mahogany veneer to match some other furniture that will be in the room. I will most definitely put up some pics once they are finished and in their final home.
One last question on these...the open cell foam I used in the box was from a craft store, and I think is used for seat cushions. I have also noticed there are "acoustic foams" available in various sorts that are much less expensive that no-rez. Are these acoustic foams appreciably different from the commonly available open cell foam? If so, I may consider swapping out the foam when I pull the speakers back apart for final finishing.
Thanks much, in particular to you Danny for designing such great kits and making them available at a reasonable price.
Rick.
