What kinds of crafts can you do with children on Chol HaMoed? Making objects with clay, cutting, pasting, painting, weaving with paper/string/knottting yarn? Thanks so much! Pesach Semaech!

ב"ה מועדים לשמחה Shalom Although all the things you mentioned are forbidden for adults. However for small children since these things keep them occupied are considered things which are for the sake of Chol Hamoe'd and they become permitted However, activities which require intricate work which are usually done by older kids, would be like a professional craft and should be avoided. All the best of health and חג שמח