I think it depends on the context. If it is "I can see bears and metal drums", then you would have to repeat the subject and verb, effectively saying "I can see bears and I can see metal drums".
As per The Klingon Dictionary (6.2, Complex Sentences):
When the subject of both the joined sentences is the same, the English translation may be reduced to a less choppy form, but Klingon does not allow this shortening.
If you are just talking about lists of items without having a complex sentence, then I would think this sentence from 5.3 (Conjunctions) applies (even though it is about the post-verbal meaning of je):
As in English, the meaning of such sentences is ambiguous: [..] The exact meaning is determined by context.
If there are bears and metal drums, then presumably you're not talking about bears, metal, and drums. An oft-quoted example where there is an ambiguity in English is I am dedicating this work to my parents, the Queen of England and the Archbishop of Canterbury. Without a comma before and, the list could be mistaken for an apposition. Obviously, the context makes this interpretation highly unlikely!
Just remember that language is rarely unambiguous and independent of context; any attempts to avoid this make it very unwieldy. Which is why legal language is typically so hard to read.