If you're trying to create a "mould" I managed it by putting an exact in-line block for the boolean with the rear section
a single multi-block boolean failed for me
I presume the others would work this way too and then merge them.
It's true that the 3 objects are duplicated, but to fix it, you just need to delete the extra 3, leaving only 3. Could you delete them? That way I don't have to send you the file again.
