You may ask, what are the best 3D models for selling 3D prints?
Generally speaking, if you sell your products on online marketplaces like Etsy and eBay, you have a MUCH higher chance of getting found IF your products are niched and commonly searched.
Customers don't usually wander around these platforms, they search for something SPECIFIC.
IF you are printing and selling, for example, a beautiful statue, you have a really really small chance of customers finding you.
OR if you sell Harry Potter or Marcus Aurelius statues you have a much higher chance of getting the order.
You have to sell products for exact audience needs. Something that someone would search for.