Do you sell hair for re-rooting?
No.  See the question below for hair sources. 

Where do you get hair for re-rooting?
I prefer to use real MLP hair, however, now there is nylon hair which has a texture identical to 3rd generation hair.  It is pretty darned expensive, though.  Hair can be bought on-line from various sites or locally at beauty supply stores.  People use synthetic hair for making hair extensions, dreadlocks, & ponyfall hair pieces.  Look for "loose hair for braiding".
Here's a table on some "hair basics".

Can I use MLP manes for re-rooting?
Yes, you can, but this is even MORE tedious, if you can believe it.  You will need to secure the cut end - either by glue or knotting or both.  Some people melt the ends with candles...but I've never tried this.  Also, your manes will be shorter.  The final result will depend on the original length and how much you lose from cutting/securing the ends.  Please see my Pony Clippings tutorial.

Waaah!!  I don't have access to hair.  What else can I use?
A little creativity?  I've seen customs made with: DMC embroidery floss, yarn, your own hair, your horse's hair, wool, clay hair, beaded strands, wire, and even no hair at all!

I'm looking for a certain type of hair.  Fluffy, thin, and more fur-like.  Where can I find this?
Hmmm...you could try using some specialty yarns or perhaps alpaca fiber.  Or check the fabric store for plush fabrics.  Another option would be to transplant it from a stuffed animal.  Bear in mind that if you use "natural" fibers like wool or alpaca, you have to protect it from moths.  Some people use mothballs.  I prefer Deep-Woods Off's lavender packets.

Where can I get tinsel for ponies?
There are several possibilities: buy it from a custom supply provider, take it from a donor pony, or search for tinsel that was not specifically designed for ponies.  If you are not concerned with the width of the tinsel or exact color matches, some Christmas decorations or gift wrap tinsel will work in a pinch.  If you want finer strands, try digging through your fabric store's selection of "fancy/special occasion" threads.  Another option: fraying the edges of metallic fabric. 

What advice do you have for someone re-rooting with tinsel?
It is delicate and can snap easily.  A lot of tinsels discolor/melt with heat.  Keep this in mind when styling the pony - test a sample first.  Tinsel also requires extra time/effort in prepping and re-rooting.  Not to mention the extra cost.  A roll of fancy thread can cost $4-6 US dollars!  If you're making the custom as a commissioned project, please keep this in mind.  Also I DO NOT recommend using tinsel in your very first re-rooting project.  Practice with plain hair first, to minimize your frustrations! ^_^

What type of hair do YOU specifically use for re-rooting?
Currently, I've been using a lot of kanekalon and nylon hair.  It just depends on the look I'm trying to achieve.  If something needs curls, I'll go for kanekalon or nylon hair.  If something needs super shiny hair, I'll reach for the saran hair.

What is a skein?  How many ponies can I re-root with a skein of hair?
A skein is an imprecise unit of measurement...like a "basketful" or "wad" of something. The term usually refers to a roll of a yarn.  Some people use it to refer to a roll of synthetic hair.  The size of the skeins varies...it depends on who you buy your hair from.
Also, the number of ponies you can re-root with a skein of hair depends on your technique/style of re-rooting.  If you like the hair super long & super thick, you will need more hair.  The estimates from the table above are for average length hair rooted in a thickness similar to the Hasbro originals.

What do you use to secure the tail in the pony?
I prefer either plastic or stainless steel washers...they're both fairly expensive, but they won't rust.  You can buy these at any hardware store such as Home Depot, ACE hardware, or Lowe's.  Some people use string/ribbon.

Where are the instructions for re-rooting?
Okay, I finally got around to writing a re-rooting tutorial.  It's right here:
http://www.aikarin.com/mlp/customs/rerooting.html

C'mon!  Isn't there a faster way to re-root?
Re-rooting is tedious no matter how you do it.  Most customizers think this is the most time-consuming part.  So, pop in a music CD or grab a friend to talk to and start re-rooting!!

Where are the instructions for re-tailing or making a replacement tail?
Glad you asked.  There's a tutorial now.  It's here: http://www.aikarin.com/mlp/customs/tail.html

How do I re-root a Brush n' Grow Pony?
LOL, that's a great question. Unfortunately, I've never done it before and I've only seen ONE instance where someone re-rooted a BnG AND restored the mechanism to working order. I have a bait Brush n' Grow pony that has been headless for years. It might be possible to glue the mechanism back in place, but I haven't experimented with that yet.  The parts will be delicate after gluing, so this is not the best idea.
If you don't care if the tail works or not, you can just remove the mechanism and glue the head back in place.  In this case, she will be a non-Brush n' Grow.

How do you dye hair?
Below are really basic dyeing instructions.  Not all hair types will take dye (see the table above).  Most customizers use Rit fabric dye.  This is available in craft stores & general merchandise stores like Target or Wal*Mart.  The liquid form can be painted straight onto the pony's hair.  The powder form needs to be dissolved in water first.
Just apply to the pony's hair & let it sit.  If you want it darker, let it sit longer.  Try not to get any dye on the actual pony.  I use shallow dishes for dyeing hair.  Then, rinse the pony's hair in running water.  Yes, the colors are much lighter after this step.  I usually wash the pony's hair in shampoo to get rid of the residual dye.  Using a vinegar soak afterward is optional.  Rit dyes aren't true "acid dyes" (which require vinegar - dilute acetic acid), although some colors are blends containing acid dyes.

Should I dye the hair first, then re-root, or dye the hair on the pony?
If you have a choice, dye the hair first, then re-root.  If the hair is damaged by the dyeing process, you can always dye another batch.  If it's already on the pony, you would have to re-root it again!

Can I dye a pony and her hair without taking her apart?
Real MLP hair will take dye well, but the colors are unpredictable. Try testing the dye on the tail.  That way, if the tail color doesn't turn out well, you can easily replace it.  Also, the body & hair may take up dye at a different rate. You will have to take the pony apart first, since most dyes contain salt and this will cause the tail ring to rust.

What about special effects like gradients & stripes?
Use a paint brush & apply the dye to dry hair in a selected area.  Let it sit, rinse as usual.  Your results will depend on the type of hair used.  See below for more details.

The hair isn't dyeing the way that I want it to.  Why?
In general, synthetic material like pony hair is hard to dye.  The results depend on the type of hair you're using.  Some hair will dye well, others will not.  The hair may not end up the color on the dye package.  Why?  Well, because the dye was meant for natural fabrics, not synthetic hair!!  The only way you can tell is by testing it out.

I dyed my pony's hair and now it's seeping onto the pony and staining everything.  What can I do?
Unfortunately, this is always a concern with dyed hair or dyed anything for that matter.  I would try washing the hair very carefully (as not to get the pony wet) with some shampoo.  It's best to shampoo the hair after dyeing, to get most of the dye residue out.  However, it may not solve all of your problems...over time, dye may still leach into the pony's body.

Can I bleach pony hair?
The only natural color that is truly "bleachable" is the fading pink color found on Posey, Wind Whistler, G3 Minty.  You can bleach that color by leaving the hair out in the sun.  Bleach may or may not alter the other colors.  The only real way to know is to try a sample.  I accidentally bleached a Moondancer tail one time and it turned an ugly maroon-brown color.  I would say it's nearly impossible to bleach pony hair to 100% white (except fadable pink).

Can I dye the hair on a so-soft?
It's possible, but you'll probably end up dyeing the flocking at the roots as well.  There really isn't a good way around this.

How do you curl hair?
There are several ways to do this.  The easiest & safest way is simply to get the pony's hair wet, comb it straight while adding a tiny dab of conditioner, then rolling it in a curler.  Let it sit for a few days.  I prefer the sponge rollers.  The longer you wait, the tighter the curls.  Then, carefully remove the curlers.  Curls will soften with time.  I don't recommend using hairspray on ponies (which can damage hair & symbols).

Can I straighten curly synthetic hair?
Well, it depends on the hair type.  If you want straight hair, it's best to start with straight hair.  Some people use curly doll or extension hair for re-rooting, which may be easier to find.  The composition of the hair is usually not listed...who knows what's in there.  Test an unrooted lock (NOT attached to the pony) before trying anything on the custom itself.  Mist the hair with some water & use an iron set on the lowest temperature.  Hopefully, it won't melt under the heat.

How do I straighten Yaki/Jumbo Braid kanekalon hair?
It's tedious, but I do it in two steps.  First, before re-rooting, take a small handful (about 1" wide) of the hair and mist it lightly with water.  Use a curling iron or straightening iron set to the LOWEST setting.  Fold the hair in half and hold it by the folded part.  Run the iron through the hair several times, while pulling it against the iron.  Make sure your curling iron is straight...don't have it angled.  Be VERY alert that the kanekalon isn't melting or getting frizzier!  Spritz more water on it and repeat a few times.
Then, allow the hair to dry.  After it is completely dry, re-root the pony.  When you're finished with your painting and customizing, it's time to style the hair.  Trim off the scraggly ends and mist the hair.  Rub a small amount of conditioner into the mane and tail.  (Note: I wait until the end to add conditioner, because if you get it elsewhere, it might keep the paint from sticking to the pony).  Use your curling iron set on low to do the final straightening.  Once again, be very careful not to melt the hair!  If you want curly kanekalon, it will look better if you straighten the hair first.

Where can I find dark gray hair?
Hmmmm...as far as I know, there isn't a pure dark gray synthetic hair out there.  One visitor pointed out that Dollyhair.com has a color called Hematite, described as "dark steel silver with a hint of plum."  Update: I have a sample of this color on hand and it is so dark that it's almost black.  It's basically black with muted purple highlights.  A gorgeous color, but I think it's way too dark to be called gray.
There is also a white/black blend in Kanekalon.  After de-frizzing, the separate white/black strands would be more noticeable.
Another option would be dyeing light silver or white Kanekalon.  Or white colored real MLP hair.  I'm not a big fan of dyeing...it usually gets everywhere on the pony (and it can even rub off on other ponies).

How do I get rid of that freshly re-rooted poofy hair look?
Hey!!  Some people actually like that "swept" hair look!  If it's not for you, try wetting the pony's hair, then hold it down with a rubber band.  After some time, the hair will stay flat against the pony's head.  Alternately, you could wet the hair, hold it flat, then use a hairdryer on it.  **please note: be sure to test synthetic hair first!!  A lot of synthetic hair brands including saran hair (katsilk) will melt with heat.**

How do I deal with "fly away" or static buildup on hair?
Move to a humid environment.  LOL, just kidding!  I live in a very dry place, but my ponies have well behaved hair.  How do I do it?  It's actually very simple.  First, wet down your pony's hair.  Then apply a tiny dab of hair conditioner & comb it throughout the hair.  "A tiny dab" for me is a thin coating on the pad of my index finger.  About the size of a dime.  If your pony's hair feels greasy, you've used too much.  Style & let the hair dry on its own.  You don't need to rinse out the conditioner.

What brand of hair care products do you recommend?
*scrunches eyebrows*  I just use whatever I have on hand.  Usually Pantene's Smooth & Sleek or Thermasilk.  They seem to be more expensive, but you don't have to use as much, so the cost works out to be about the same =)