I got into customising My Little Ponies last year. I've only actually completed two, the first was a Thalmor and it wasn't very good, but I think that this one, considering my experience in such things, went really very well.
I didn't paint the body. I'm not very confident when it comes to skills like painting things like that, and I really enjoyed it so I'm going to get an airbrushing kit at some point to make it a little easier. I did reroot the hair, and I remade the ears, albeit not perfectly. If I had given it a full body repaint then the ears would have been much better because I could smudge the clay into the plastic rather than having to set it apart.
First I started with the Petal Blossom pony. She's amazing because she has the best pose, frankly, and I've always disliked any pony outside of the 3rd generation. Plus, fortunately, 3G ponies are the easiest to find, though perhaps the toughest to customise because they are imfamous for bucket tons of glue. I couldn't pull her head off, and neither did boiling it work, so I had to go to the third and final option to rehair her: I had to cut her head off. I took her face off with acetone first because I am a little bit ridiculous and can't stand pulling their heads off if they still have eyes. Once I had her head off, I cut the hair and removed the roots from inside the head with needle-nose pliers.
Next I rehaired her using Bluebell nylon hair from My Little Customs. As you can see the hair always looks quite greasy and unpleasant when it's first put in, but it isn't actually greasy. The best thing to do once you've rehaired a pony or doll is to wash the hair with either shampoo and conditioner, or a 2-in-1. It sounds silly but it makes a massive difference.
I next fixed her head back to her body with E6000 since I couldn't push it back in place after cutting through the plug, then I painted her eye with standard acrylic paints, white first, then silver, and added eyelashes with a fine brush, and then added some green Night Elven markings around her eyes. I then sliced the tops of her ears off and took some jewellery wire and hot glued it in place, using rubber earring backs (making jewellery for a living gives added perks to other crafting projects, as you can see) to hold them in place while I applied the glue. Then, finally, I added polymer clay around the back end to create a sort of skirt.
I had to tie her hair back for the next step, which meant it needed washing again afterwards because the nylon likes to conform to the shape it's left in. I added some more polymer clay around the neck, and added a small chain as a visual way of keeping it together. I made some small feathers and leaves in different sizes out of clay and after cooking just those pieces, pressed them into the still soft clay around her neck. I must have made about 50 leaves and feathers overall, and only had about 7 left over at the end. I did remove them later on and paint them before replacing them. Once that was done I added a strip of clay on top close to the neck and left it flat and bare.
Next I added clay over the ears, then I added vines here and there before cooking the whole thing (I won't use polymer clay on a pony again - her mane split despite following online advice to lower the temp from what it would usually be for the clay and reducing the time). I painted her skirting, the rests of her shawl, and her ears. They're not perfect, and I did my best to match the paint to the natural pony colour, but like I said at the beginning, I'm not brave enough to try to repaint an entire pony by hand without an airbrush, and aerosol cans/spray paint usually flakes off. I rewashed her hair, too. I had to towel dry the moisture out of it, then brushed it and left it to air dry.