I can help you. What you need to do to create an OC is to pick a monster or villian that isnt already a character and research it. An example would be an alien. Look up myths and such of aliens. Once you have mastered that, your character needs a name. For an alien, you should think of a futuristic name or another creative name. Have you heard of the Jetsons? The character's last name could be Jetson. See, it's that easy! After that, you character needs a look. Don't make her look like an existing character or a character somebody else created. On DeviantArt, Candy2021 made a fangtastic graph thingy on plagiarizing other OC's. You know, I think she has an account on here. You could ask her about it if you want. Unless you are an expert at drawing MH, I suggest using a pre-made base. Dazzle1026 on DeviantArt has made a few, I ise her bases all the time! Once you have drawn her, you need to create a profile. Have you seen the profiels in the back of the doll diaries? I advise you to use those topics. Write the profile like you ARE your OC. Use the dolls' profiles as examples. After that, congrats! You have sucessfully made an OC! As for creating dolls, I can't help you that much, but I would buy a cheap blonde Barbie and practice on her before you spend $20+ on an MH doll, in case you mess up. I always color the Barbie's hair with colored Sharpie. I hope this helped, good luck!