I think 3DP might be a company name and is not commonly used to abbreviate 3D printer.

If you're paying someone to create your models, your investment in a printer of your own may pay for itself in less than a year.

To print your larger items, you would need an appropriately large print surface. One might expect that for the smaller figures, a resin printer is indicated. It's easy to find inexpensive "starter" printers for the small stuff, but just as easy to find larger capacity printers. You can't go wrong with the higher resolution resin printers, those advertising 4K or higher resolution. Look also for a reference to mono screens, which generate sharper detail than color versions.

For the model material, you have any number of resources, starting with the descending-in-favor Thingiverse, Prusa (forgot the resource name), Thangs, many others. Some resources are merely links to other sites, but if you find what you seek, that works too. When you find the printer to meet your needs, the vendor will find a reduction in income. At this point, you can suggest to purchase model files from the vendor, returning some of the income.

Also, for modeling requirements, Reddit has a couple of sub-reddits that put requests and creators together.

I've noted that there's a trend in the industry forcing the users to slice the models using only one specific program, due to the hardware being locked to the software. I would have thought this violated anti-trust laws in the USA, but then again, these devices are not manufactured in the USA. Proprietary anything grates on me.

I've been using a paid subscription to Lychee Slicer, which is quite a well-written program, but it has a subscription requirement, which will increase next year after my introductory year expires. I've found another similar slicer, Formware 3D that has a single-time purchase as well as a 30 day free trial.

Be sure to pop an update here now and then, and any other questions that may arise. If you have a web page showing your work, share it with the world here.