In English agent nouns are created by adding “-er” to a verb. English being English this is sometimes done with “-ir” or “-or”. “-er” is also used for comparatives. Some agent nouns, such as “artist” use “-ist”, although “-ist” is more commonly used for someone who holds a belief or follows a philosophy rather than someone who performs an action.
For Diinlang it is obviously desirable that there is only one way to create an agent noun, and that this be of a form that is distinct from other word types.
An option I considered was to use the suffix “-or”. This could be gendered as “-oro” for males and “-ora” for females. Inanimate objects that perform an action would be designated by “-it”. Thus if we used the work “kuk” for the action of cooking a cooker or stove would be a “kukit”and the person using it a “kukor”, “kukoro” or “kukora”. (This is just for illustrative purposes. The final world for “cook” may be quite different)
It occurs to me that things can be made simpler for the learner. The word “du” is used for the verb “to do”. We also have the pronouns “zo”, “za” and “ze” to indicate male, female and neuter/unknown. This might give us “kukdu/ kukduze”, “kukduzo” and “kukduza”. Unfortunately if the verb we are modifying is “du” this gives us “dudu” or “duduze”. The syllable “du” is probably redundant which suggest that agent nouns be created by the simple expedient of using “-ze”, “-z0” and “-za” as suffixes.