Dolls can be made of many materials, the more magically permeable, the easier it is. Some like iron can only be used when it rusts and it lets the magic of time and change in. Some like clay are easily formed. This is why most dolls have ceramic parts, even if it's just small mechanisms. Good anchors for the threads of magic. Even the strange dolls of the Witch of the Ending Of Things, wrought of stolen flesh and twisted metal might contain an old spark plug or the most advanced combat dolls may have ceramic composite in their armour.
The Potter Doll theorised this is why tea is so important to the health of dolls. For tea is intrinsically linked to the cup it is served in, as the magic is linked to the doll. Whether this is true or not, magic doesn't care, it is enough of a belief for it to work.
Each cup the Potter Doll makes takes four stages to make. First she takes a small scraping of ceramic from the doll it is for. This puts a little of that doll into the cup. Second, she uses clay that contains some of her own dust, from wear and tear as it works so hard making them. Filling each cup with her own magic and love. Thirdly she spins them on the wheel, carefully and efficiently, shaping each into a unique piece, inspired by the doll it is for. This is why many doll tea sets have a unique cup for each doll. Finally it is glazed and fired in a magical kiln, powered by a tiny fire elemental. The Potter Doll feeds her elemental friend small pieces of charcoal she makes her self from magic woods as well as good quality oak shavings and linseed oil. Occasionally she gives the elemental gunpowder as a treat when it's been working particularly hard.
The cups from the potter doll hold some of the magic once finished. They repair themselves, and change over time, to reflect the state of the doll that owns them.
It is the latter thing that has lead the Potter Doll to a different theory, that perhaps repairing a broken cup will help heal a broken doll. It is because of this that the Beggar doll sits in her study, tightly clutching it's cracked cup. The Tea Doll had sent it along when it tried to pay for a gift of a cup of tea. Dolls look out for other dolls, and gifts are given freely.
The Potter Doll couldn't repair the cup fully, it's link to the broken doll was too strong for it's magic, but it was able to patch it with a little resin and clay, small doll magics. The Beggar doll looked a little less broken too, clutching the newly repaired cup, payment refused again. Dolls look after other dolls.
