The eyes and mouth seem to be made of paper so they can change and everything. And the eyes also have some rhinestones to look extra sparkly.
The eyebrows are most likely painted on the dolls and the noses are painted on too.
The hair they use doll hair and they sew the clothes but my question is:
Which doll base closely resembles what they have? Cuz to me it seems like an existing doll base rather than a custom one and it looks familiar but I can’t put my finger on it. Doesn’t have to be exact as long as it’s close
The heads remind me of Daiso doll heads but I’m not sure.
It sounds like you already have so great ideas for customizing the dolls! As for finding these kinds of dolls, you might want to try a reverse image lookup (like Google Lens or similar) or ask a doll or Japanese doll forum, FB Group, etc.
I’m not familiar with those doll bases, but you could always visit a Goodwill or resale shop and look for some cheap fashion dolls to practice on. That way you can find something inexpensive to practice on that fits the look you want for your doll. You can use acetone/nail polish remover to remove painted on features.
Good luck! I hope you find something you love and share pics of your custom doll with us. That’s a really fun idea.
From a quick search I did, it looks like the doll bases they use for this web series are Pure Neemo dolls, made by Azone International, and soft vinyl anime doll heads, probably also made by Azone.
I hope this helps in your search.