I've worn HK hair extensions since they were known as Headkandy and sold on their own site by the same name. In the last few years they've moved over to dirtylooks.com but the quality hasn't changed, they're the nicest extensions I've ever worn and are lovely and thick.
As my hair is naturally so thick I have buy two sets at a time; what I'm wearing at the moment is just under two, as I cut the ones I was wearing at the top of my head to blend in with my layers, and they're too short now that my hair is finally growing. My hair is naturally just past my shoulders, and I wear the 16-18in extensions.
I can't wear extensions straight because they don't blend well with my natural hair if it's humid and starts going a bit frizzy, but I was getting bored of just wearing them waved with a wand all the time, so I dug out my Sleep in Rollers and thought I'd give them a try.
There's two ways I use them on my extensions, and I love both effects.
Method 1 - Rolling ahead of time
The first way is to split the extensions up in the order they go into my head, with 2-3 in each pile. Then I comb them through, section into roller-sized bits (2ish inches) and dampen them with a little water, spray with a bit of Bedhead Queen for a Day spray (thickens and helps to hold the waves/curls), roll a roller up them and then secure with 2 bobby pins, one on each side of the roller. As you can see above, I use a mix of big and small rollers, small ones on the bottom few extensions as well as the top layer, and the bigger ones throughout the mid sections. I do it like this because the smaller curls hold better and the bigger ones give more bounce and I like that combo, but I've tried it a few ways and all work well, dependent on the look you're going for.
Once all the extensions are rollered (not a word, don't care), I blast them with the hair dryer (gently on low speed but high heat, don't want them coming undone) and then set them aside until I'm ready to wear them. This is a great way of preparing your hair well before an event, to save time. When I am ready for them, I blast them with the dryer again and let them cool down before unrolling and brushing each section separately and then putting in as normal.
Method 2 - Rolling while wearing
The other way I use them (as seen in the delightful photo above) by plonking all the extensions in my head as normal, and then using my trusty waving wand to curl large sections at a time, then whilst still hot wrapping that section round the roller, securing and then once my whole head is done I do my makeup etc, and then take them out before I go out.
This is the full set once curled (and worn)
The only real difference between the two methods is that the first takes time up front and the curls are slightly bouncier and more wavy and glamorous, and the second is good if you haven't had time to prepare ahead but have 20 minutes or so to do your hair. The curls in the second method don't seem to last as long (because the rollers are in for less time, I imagine) but the curls are more 'curly', if that makes sense. The second method would also obviously work for extensions that you can't remove from your head with ease (aka any type other than clip ins)
Do you wear extensions or have you ever done so? Have you ever tried using rollers in them, or your real hair? Do you prefer big, bouncy hair or a more sleek look?