OCs are a large part of the OSC, and they can range from looking like a classic BFDI character, or something out of an professionally made movie. There is a bland to interesting scale when it comes to object OCs, and while it is okay to have a more plain OC, you definetely can make something cool. There are three rules I have to making object characters that are interesting. These are:
1. Nothing is saying you must keep it in the original style.
2. Personality shouldn't focus on a disability.
3. Stories can tell a lot.
Focusing on rule one, Let's make an OC's design. I have a thought, and it's an iron OC which looks like a beetle. We can start with a base like this.
And from there, we can do something interesting. Why not give them six legs, since they're inspired off a beetle?
While we're at it, let's incorporate a personality to enter rule 2 into the character. One of their legs doesn't work! How terrible. We don't have to make it all the character has for a personality, nor does it need to be part of their personality at all! I think for the personality, they'll be a bit shy, but kind when you get to know them. But that's personally not specific enough for me. Let's incorporate a concept. I kind of like the concept One by Cheesy HFJ had where some of the objects had to hide their sentience from humans. While I'm not sure if Cheesy was the original person with the concept, but I sometimes use the concept as an example, as this character is meant to be. Let's rewrite it a bit. Due to having to hide for long periods of time, Ironbug (the new name of our character) gets quite shy around other objects. Over time, they'll get used to them, and end out being extremely kind. Much better.
For rule 3, a story can say something about a character. An okay story for example, following our concept, would be something like this. "Ironbug has lived with humans for a long while. When they started meeting more objects, they thought they knew they were not the only one alive." A large part about all these rule, which you may or may not have noticed is detail. Detail is an important part of making a character. Perhaps in the design, and the writing that goes into the descriptions and stories involving the character. How about we add some more details to the story? "As long as Ironbug has remembered, they have lived with humans. They have been passed down from thrift shop to human for years. They've had to hide their sentience for all of this time, except for at night, where they would snack on rasins and cloth. One day, they were suddenly thrown in a landfill, where they found more objects. It's very different, as Ironbug thought they were the only sentient object in the whole wide world." This is a much greater idea, and gives more context. That's about it about creating cool OCs.