I don't think you can do this directly but there are many different ideas can help:

1- The first idea link your object with one2many object , and in the new object use fields.Char() / fields.Float() do define your field

2- The second idea is to define text field , and in this field insert you list of strings or float , and if you want to use this list in python use method "exec(mycode)" to convert it to list