Bought 2 modifiers for the YN-568EX. A stofen (know what that is?) and a 1/8" honeycomb grid.
The stofen, which is the white tupperware thing that stick on the front of your speedlight to diffuse the light (not to be confused with soften!), was under 5 bucks and it shows. It is definitely inexpensive. Does it work? It snaps on, snaps off and the color balance seems to be right, so I would say yes. Holding it next to my Nikon one, it is quite embarrassing! I just don't bring them out at the same time.
The honeycomb grid is pretty neat. It has the strap to go around the flash head and the velcro straps to strap it to the strap. You know, that strap that I have to take off every time I use my SB-910 in the bowens speedlight adapter?
BTW, the YN flash fits and I occasionally use a Minolta 4000AF and Vivitar 285 for flash and I think that the 285 will give me fits on the bowens because of the lip around the end of the flash head and the 4000AF I think is a little bigger. I am usually using the YN flash in the softbox anyways because it fits with the velcro strap on. Haven't tried the other two flashes and I probably should have put this in the the Neewer softbox/adapter post. Oh well, if I remember when I'm done, I'll copy this in there, but I digress.
The actual honeycomb part feels like the fins on a radiator. VERY thin as most of these are. The ones I have had in the past were for full strobes and a bit thicker. I suppose they are normal for a little head like this? I'm kind of scared to press on it because they may crush easily. It didn't come with a case, so I may update this the first time something rubs against it and squishes the edges, or not. If it lasts a dozen uses, it will be worth it.