Okay, if you must, go ahead and get the whole "if you bought it, it's not a DIY project" out of your systems. I'll wait.
Still here? Good. This is a review of the DIY Ring Flash Kit from DIY Lighting Kits, the retail venture of DIY Photography.
The DIY Ring Flash is sold in a kit form, and ships in a flat envelope. As one commenter put it, it looks like you're assembling an oddly shaped pizza box until you're done. It has an inner section made of cardboard which has an inner reflective surface, and an outer section made out of black vinyl quite similar to the material that three-ring-binders are covered with.
It's quite easy to assemble, for the most part. You should pre-crease the folds of the cardboard bit pretty good before you start as this makes assembly easier. Also, if you're fussy like me, wear gloves so you don't get fingerprints all over the reflector. I used some cheap disposable cotton gloves I have to wear when I'm making prints. The instructions aren't clear on whether or not the center ring goes inside or outside the center aperture: the manufacturer says it's meant to go outside (which is much easier) but I put it inside because I thought that looked better. If you do that be very careful not to mess up the ring by bending it. If you bend it it will crease and you will get a dull spot. Since I didn't do that I don't know if it would be a big deal (I suspect not) but just avoid it and you won't have to care.
You will want the optional bracket. Just buy it when you buy the flash and save the aggravation. I bent mine in a vise over a round form, but that's optional. I would recommend that you bend it over something with a round edge as opposed to a square countertop, it will help avoid excessive stress on the bend. The bending template has a lot of slack in it, so don't worry if your camera's not listed or you don't get the bend in just the right place. Just use the mark for the camera closest to yours. I have a Rebel T1i (aka the EOS 500D) and I used the one for the other small dSLR's (50D, etc.) Works fine. Some people have noted that they have issues using the bracket with a gripped camera: I have the Canon grip for my Rebel and I didn't notice any issues. I did bend the bracket on the conservative side so I'd have a little more up and a little less out, but it still mounts on my tripod fine and the lens is right dead center in the aperture.
I have a 580EX flash which is one of the larger on-camera strobe units you can buy. It would not fit into the flash head aperture as-is. The manufacturer is also clear about this and the fix is easy: you just cut little slits in the corners of the aperture. I made about a half-inch cut on all four corners, and the flash slipped right in. Be careful with the rubber-bands: they are very strong but do not have a lot of stretch. I broke one trying to make the pattern the example shows with the crossovers. Fortunately two seem to hold the flash fine and rubber bands are not hard to come by.
Once it's all assembled it's pretty straightforward and works like any other ring flash. Here's a picture I took while I was messing around with it. Ironically the layered Damascene steel looks better with more directional lighting but note the nice even light with no shadows.
Cheap, cheap, cheap. A powered ring flash is several hundred dollars, a plastic Ray Flash is around $200, this thing was $47 with shipping and bracket. No comparison.
It's fun to assemble your own stuff even if it's not "real" DIY.
It is a ring flash and appears to be a reasonably consistent and symmetric example of same. Insert standard ring flash "pros" list here. :)
Very fast service, although that's not related to the thing itself. I ordered it Sunday night after seeing it on the Strobist site and I had it Wednesday morning.
It's not really fair to say the lightweight nature of the unit is a con, as you are getting a $30 ring flash out of this deal and frankly, it's sturdier than I thought it would be. However, the bracket really could be sturdier as the whole assembly vibrates for a few minutes if you so much as touch it. I think I may have a machinist friend of mine make me one out of a slightly sturdier metal. I got around this by putting the whole deal on a tripod and then using my camera's remote shutter release after the vibrations died down.
The device does cost you approximately two stops of flash output, maybe a little more, I would assume both from inefficiencies and from increasing the effective area of the flash output. If somebody wants to send me a Ray Flash to compare it with, I'd be happy to oblige. With the setup for the picture above, at ISO400 and manual 1/1 flash output I couldn't do better than f7.1 without pushing the shadows too far. The unit was about three feet away from the target. (I couldn't get closer because I was using a prime lens.)
Because of the way it's constructed, there's no way to fire the thing with the flash attached to your camera's hot shoe. Well, you could, but not with the camera lens in the center aperture for maximum ringlightosity. (They are very clear about this on the site, but some people apparently don't see that.) I use my wireless flash trigger. You could also use a sync cord if your flash supports that. (You can buy a sync cord adapter for your hot shoe if your camera doesn't have a sync port. They're very inexpensive.) The other thing this means that you don't necessarily anticipate is that there is a LONG arm of stuff that goes down from the unit. You can't hold it very close to your body if you want any angle at all. It gets in the way of your tripod head adjustments from many angles and would doubtless also hinder mounting it on a light stand in certain ways.
This can make it really hard to use a tripod with any sort of downward angle. Since it also makes the thing very tippy, angling your tripod to compensate can be a real headache. My tripod (a Manfrotto) has a deal where you can take the center column and make it a horizontal arm. With this and some creative tripod configuration (it looks like a big spider) I was able to point the unit, mounted on the camera, at about a 30 degree downward angle. Any more down that that would be very tricky, especially since the weight of the flash will try to pull the unit closer to vertical. There's no way you could shoot straight down with it without some additional bracing means.
This is a fun way to experiment with a ring flash for not very much money. If you like putting things together it's fun and easy. (If you don't like that kind of thing don't buy it, period.) You get what you pay for, of course, but in this case you at least get a good value for the small amount of money involved.