Most of my dolls don't have extra parts. I was very fond of jointed hands, but now I sometimes prefer differents sculpted hands rather than jointed hands. Jointed hands can be such a pain to manipulate while taking photos! So some of my dolls have extra hands. For female dolls, I like to have heel feet (most of the time) but they are not always available. And sometimes I buy an alternative head for a doll, but not often. I calculated and in the end 1/3 of my collection has extra parts. The luckiest is my Nyxdoll Katrina. She has an extra head, one extra pair of hands, and heel feet on top of flat feet.
I don't think I have any extras for the smaller than SD sized dolls, though I'm not sure if any of them even had any available. Most if not all of my SD girls have both regular and heel feet, and if extra hands have been available I've gotten those too. Both of the guys have default and jointed hands, but most of the girls have been less fortunate and didn't have any extra pairs available. The Supias had 1 extra set and I did get two pairs of those but frankly, they are so... odd / too unrealistic looking in my opinion that I've ended up never using them, so I never bothered getting any more of them despite later on getting more of the matching bodies. I don't currently have any extra heads for my dolls. I do sometimes wish I would have gotten the sleeping version as well for one of my dolls back before her resin color was discontinued, however, I am terrible at recreating faceups and like 99,9% certain it would bother me too much if all the faces of the same character wouldn't look exactly the same except in a different expression, so, chances are I would have ended up regretting it more if I had got it. That being said, I do now have a doll on order with two heads, but since one is human and the other beast I feel like I have a much better chance at making them look like the same person, weird enough? Though originally I did order both versions simply because I just couldn't make up my mind on which one to get, but as I've been waiting I've been toying with the idea of trying to go with both.
Candell has 9 parts in total (7 hands, 2 feet), and Mina has 10 (5 hands + jointed, 4 feet). I love extra parts and I always get them all - I'd make an exception for heel legs¸ since from what I understand they take a whole restring to get them on unless there's a hook under the heel. Hands add a lot of expression to poses and it's fun to switch them around. It's one thing I loved about 1/12 figures which always had a bunch out of the box - the other is faceplates but they're hard to get a hold of in BJDs. My Dollstown will have no extras but the arch of her feet is jointed, and I might get jointed hands for her from another company (I do wish there were more options for female jointed hands). I think jointed hands have their place but a bunch of sculpted hands + jointed for more subtle poses is ideal.
Short answer: Way too many! Considering how rarely I use them. I have a few sets of extra hands feet. Usually I settle on a set I like and leave them in place, but I don't sell the extras. I do have about half a dozen extra wings for my 1 lonely Yotenshi Yuh in all the colors. That was a deliberate collecting endeavor and they get used more than the other parts do.
Mostly extra hands. Some dolls come with and extra set, or get bonus jointed hands, so I have a tiny drawer of hands. I also have those extra parts that come off Doll Chateau dolls. I removed the extra joints on mine. I don't do heeled feet, so into the tiny drawer with those as well.
I recently ordered a doll with 3 mouth parts you can swap between. The original version of the doll also had magnetic ears. I got extra jointed hands for him, so he’ll have 2 sets of hands, 3 mouth pieces, and 5 extra bits.
I have extra heads and hands for my Minifees. They kind of all share the parts though. It’s why most are the same skin tone. My Alicia is the only one who has extra hands all to herself.
I technically have an extra bust piece laying around, but that's because i needed a smaller one than what the body came with, I don't regularly change them out or anything. I'd like to get some extra hands for at least one (on-topic) doll some day, but I don't have any yet.
Took me a while to decide to mod 3 pairs that didn't fit, but Candell is now the winner with 2 extra pairs of feet (high-heel, ballet), and a whopping 12 pairs of extra hands. That's 32 swappable parts in total I'll eventually spoil everyone just the same.
most of my girls have the extra heel feet. one of them has flat feet, heel feet, and heel legs. 5 of my dolls have extra hands for different positions. one of them has 2 spare pairs of hands and heel feet in addition to her default hands and flat feet. i do actually use the extra hands and feet; i change the feet especially whenever an outfit change calls for a different pair of shoes that don't go on whatever feet the doll is wearing. i don't have any extra heads tho--- the closest i come to that is my Unoa Sist hybrid girl. she has two faceplates (regular and bully) and i wouldn't mind collecting a couple more of the Sist faces. i would continue painting them all with the same makeup style tho, so it always looked like the same doll with the same faceup making different expressions.
Most of the time I don't order extra parts for my dolls (not counting the extra bits my bigger boys came with ) but for the dolls of my dnd character i got heel feet for her and jointed hands for both her and her friend. They're my babies, so they're the only ones I really plan on specifically ordering extras for.
