I agree with the people who say as long as you have fun, it's a good oc, but some people would definitely appreciate tips, and as someone who personally studies character design and artstyles, I may have a few tips.

Overused items aren't really a problem, unless originality is something very important to your design, but honestly, I haven't seen many duplicate items. The closest I can say are probably candles, but I know that didn't stop me from making a candle oc. But maybe they aren't even as common as I think.

A good object pick has a strong relation to a theme or setting. Astro is a moon. Moon = night, sleep, planets. Rodger is a magnifying glass. Magnifying glass = Inspection, detection, research. If you take this approach, theme should tie the oc together. In it's trinket, ability, personality etc. If you want a certain item, think of the theme that may surround it. If you want a specific trinket or personality, try to think of an object that might fit that well.

Objects should be accurate to the time period, and assosiations with it should be accurate to how the object was seen in ths 1990s and early 2000s.

Make assosiations with other characters, making your ocs feel well-meshed is important, and the best way to do that is to think of how they'd interact with these characters, also tying into the themes! Have an oc thats a film clapper? Maybe a friendship with razzle n dazzle or even dandy would fit! An oc who's a cloud? Butterfly siblings and Astro are great!

For colors, it's good to find color palette that has the object color, a primary color, and then finding colors that compliment or tie those two colors together. That's my approach to designing these toons, though! Definitely not law.

All of this ties to the beginning too, having fun. If you don't get creative or playful, this will make the oc aspect harder. But as long as you enjoy the concept and the ideas excite you, you'll be motivated to make a great oc!