If tou are looking for things to design and upload to cults 3D, you are in the right place.
You can start with the evergreen categories, which are the ones that are almost always on the list of more searched categories. This makes them a good choice because you can be sure that your model will hae some views. Without the need to share it but if you can share it else ware to boost your chances to sell it.
These are self explanatory, people sear chem and they are the most searched over time. There are interesting effects during the year. You can find more information in the corresponding page.
This is an interesting graph that shows you the number of models each category has. Knowing that, you can be able to find a keyword that is not saturated and at the same time, people search it.
You don't find that you re looking for? This is an open source project, you can open a issue in GitHub or ever make a pull request. Here