The Q3O extension is attached to "object" files created with Quick3D, a program specialized in 3D modelling. Q3O is also known as a "Model file format" and it is currently considered old and obsolete. Similar formats associated with Quick3D include Q3S and Q3C.
The quick and simple way to handle your files is to get a quality piece of software, such as reaConverter. This software is extremely efficient in managing a wide range of batch conversions. As you will soon realize, reaConverter will help you avoid spending countless hours trying to figure out how to convert multiple Q3O files as once.
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