My entire head only took somewhere between 4-5 hours. We bought 7 boxes of manufactured dreads (like the ones on Ragdoll's site) at $5.00 a box (they also gave us a little discount- yay!). We used 6 boxes and a little bit of the 7th so I'm glad we decided on that number.
It didn't seem like her technique was incredibly difficult. I could never do it on my own head, but I could prolly teach someone else. What she did was first unravel some of the dread into two sections. Then she baided that into my real hair. (most likely the way someone would do regular braids). When she got to the end of the part that she had "unraveled" she wrapped my real hair and string (which was used to secure my hair and the fake hair being braided together) around the dread. She used rather long pieces of string for this. When she got to the end of my hair she tied the string to its other end and cut off the excess.
Since my hair is black like the dreads, we were able to do this. That's the first things she asked because colour matching is difficult maybe?. You can't tell there is string or hair wrapped around the dread unless you stare at it real close. I don't know how it would look on someone unless their hair was dyed to match the dreads. I know someone who is trying to get a hold of blue dreads to get her hair done the same way, but her hair is blue so it will match:)
I had this done on the 7th of February and the extensions are still tight at the top. I have had to do some maintenance on them where my real hair ends and where the fake hair ends. Mostly it was just a case of the string coming loose. *shrugs* I've been fixing them here and there for the most part with those tiny black rubber bands and in some places the string we had left over. I used the rubber bands because it was just quicker and easier to put in by myself- and again you can't see these unless you stare. I should probably have someone come over and help me do some maintence the none slacker way. Hehe.
I have been adding the leftover dreads to my hair when it's in pigtails or just pulled back in a ponytail to achieve even more "bigness" hehe. I also bought a box of "Jamaican"? (I think this was the name) hair that look a lot like the manufactured (nubian) dreads, but are way softer and take on somewhat of a spiral shape- if you pull on them they spring back into place. All I do is put a bobby pin at the center and then stick it in the mass of pigtail:)