Heather's Transform costume, also known as Princess Heart, is very special in many ways, and a very interesting cosplay.
On her head she wears something that would be best described as
"it looks like some sort of fancy headphones with antennas". The earpieces are very big half globes with yellow and slighty salmon
pink circles. They are connected with a cobalt blue head band. Out of each earpieces comes a little olive green antenna with light yellow, glowing globes on the ends.
With this costume Heather actually uses some light pink eyeshadow, lipstick and a hint of pink blusher.

Around her neck she wears something that resembles a pink belt
with a big red, silver framed heart on the front.
Now here is one of the things that is special about this costume.
We all know that Team Silent goes crazy with making details look
as realisitc as possible, but here the belt holes look like white dots painted on the pink belt instead of real holes. Same thing happens with the bigger version of the belt which Heather wears around her hips, from further away the white dots look like belt holes through which you can see the white dress, but up close they look simply painted.
Just like the big pink heart on the front of her dress, which in the game actually glows in the dark. Its color is darker in the middle
and turns more pale towards the edge.

It is rather difficult for me to define what material the dress itself is made from. I think it is some thin, non shiny vinyl, since the material seems rather stiff especially in the skirt area. It does not wrinkle nor does it flow softly enough to be normal fabric.

The dress shows a little bit of cleavage and has a deep red stand up collar and has several dark, ornamental seams. Also on the sides from under her arms down to the hem the dress has some sort of button tape. This too look more painted though than actually being a 3D detail, so it is your choice if you want to draw it on the dress or sew the ornamental seams and buttons to it. The latter might make your costume look more convincing though, same with the white belt holes. The shoulder pieces of the dress are another one of those weird things. Big, almost completely round and of the same pink as the pink used on the earpieces of the "headphones". The armholes are golden metallic rings with blue, red and yellow gems embedded.
Heather wears a belt with a heart around her hips which is a bigger version of the one she wears as a choker. Deep red, long satin sleeves should be the easiest thing to find, especially during prom-season.

Heather's boots are cobalt blue and have a pink soles and lining as well as a fine pink line on the top edge. The front of the boots is V-cut, the upper back has a very slight v-cut to it.
On the sides the boots show a row of five white stars each. Looking painted again but if you get flat little 3D stars and glue them to your boots it will look nicer.

I used white vinyl for the dress, for the collar I used denim that I dyed red because it is a firm, stiff fabric and would stay in shape better than thinner material. I still had to starch it though. For the pink heart on the chest I used plush and spraypainted it. The button tapes on the sides are real.

I sacrificed my V.01 Heather boots and glued blue and pink vinyl all over it; carefully so there wouldn't be any unnormal seams. I really have to stretch and twist the vinyl to make it look right. This is rather difficult though since you have to wear the boots while doing this to keep them in shape. So have someone help you with that. The stars on my boots aren't painted, but little silver stars that I glued onto the sides. The sleeves I simply bought at a local store.

For the two pink belts I used some cheap belt that I covered with some more pink vinyl and painted the white belt holes on them. My local crafting store supplied me with clear plastic hearts which I spray painted red on the inside to make sure the paint won't rub off later.
My "headphones" originally were ear muffs; I covered the connection part with the blue vinyl and attached two big half globes to the sides. I drilled two tiny holes in them to put the antennas in. For the yellow globes on the ends I used styrofoam balls.

The shoulder pieces most probably were the most diffult things to get done. Eventually I used two plastic balls for kids and cut two holes in it to stick my arm through and have it sit around my shoulder. The balls originally were way bigger than the shoulder pieces, since when you cut holes in them not only the airpressure is gone, but after a few days the expanded rubber/plastic will tighten and shrink. Because of that I had to paint them twice since after the first time painting the material shrunk and the paint started peeling off.
The golden ring with gems is atually nothing else than a big strip of flexible cardboard, painted and plastic gems glued onto it.