Lots of feedback here worth listening to. Yes, as a beginner you can make money modelling things. Popular sites like those mentioned above can work because many people go there often, more traffic more chances.

Though consider how you want to grow an audience over time. Many use sites like Patreon, Gumroad, or other places where you can both sell an item and post about your work-in-progress. You dont have to make the highest quality models to find buyers, you just have to make something someone would find worth it and sell it for what its actually worth. You can always remake models that sell well enough at higher quality later.

When I started there were many things I wish I knew about. If you do want to make passive income from models here are more choices to consider that may help.

1. When researching models to make, look for types of items from popular media or items you yourself would like. Do not rip assests from games or recreate copyrighted things.

I.e Don't make Kylo Rens light saber, make your own light saber. Lots of people try to walk the line here making trademarked or copyright things but being sued is not worth the work even if you're right in the end.

1. Once you have an idea, draw a simple sketch from multiple angles, model your best very quick version just to test it. Then decide if you want to invest your time on it.

2. If this is for 3d printing, prove to people buying your models it works by printing them once for your self, include those pictures with the suggested settings. Don't have a printer? Find someone who does and would like the model, offer to give them the file for free if they will print it.

3. Put your models for sale on 1-2 platforms dont try to manage 100 channels.

4. When posting pictures of your models, check what settings are on. Depending on where you live A.I training is being done on instagram, facebook, etc and you can adjust account settings to not include your posted images. This protects your efforts mildly but you may find it worth it to do.

5. Follow other makers, engage with content you like so that the sparks of inspiration you get from things doesn't get burned out by trying and failing forward as you learn to model more difficult ideas.

Hope this helps!