Did you know that you can get a large number of Creative Commons Licensed images in a variety of sizes as well as a few different file formats for free from Wikipedia? (note that it's important to check the licensing restrictions of the images by clicking on them, as detailed below, instead of just assuming that they're all Creative Commons Licensed (some may not be)).
For example if you're a 3D modeler looking for US Military Aircraft Insignia you can check out a page like this one:
United States military aircraft national insigniawhere if you scroll down the page quite a ways you'll see various images depicting the various insignia utilized on US Military Aircraft over the years. In this example the thumbnails are in .png format, BUT if you right click on them and choose something like "Save linked content as..." you'll get the scalable SVG format of the image, left clicking on the images will take you to an image preview page on the Wikipedia site with a large "More Details" button that when clicked will then show you a page with all of the information about the particular image, including licensing information. On that page if you want to you can download the image in various sizes sometimes (usually in .png format) by using the right click "Save linked content as..." method I described above, the link that's labeled "Original file" where you can either open the image by clicking on that link, or by using the right click method I described earlier to save the image to your computer for use later (same applies to the links to the various sized images listed there too, though those are usually in .png format even if the Original file was in .svg format).
If you're a digital artist sometimes if can be helpful to use images like those in various parts of your own works (keeping in mind to follow any licensing restrictions that may apply), even if you're someone who does things like building plastic model kits and you need to make your own decals, images like the ones I mentioned above can help you to do that (again providing that the licensing of the image permits it). Or in several cases the images can be used as 'reference images' for various other types of artwork such as sculpting, drawing, painting, creating an actual 3D model version of what's depicted in the image......
Just make sure you pay attention to any licensing restrictions on the source image, and of course try to be nice and give credit where credit is due if you end up using the artwork in your own projects.
Hope this helps some of you!
P.S. - Here's a hint at what to look for in your browsers right click menu to be able to use the right click save method I described above (the example I gave above is for Opera on Windows):
Chrome -- when you right click on the 'Original file' link choose 'Save link as...' to save the file in the original format.
Internet Explorer 11 -- when you right click on the 'Original file' link choose 'Save target as...' to save the file in the original format.
Safari -- when you right click on the 'Original file' link choose 'Download Linked File' to save the file in the original format with the original name. Choose 'Download Linked File As...' to save the file in the original format but with a different name.
Firefox -- Same as for Chrome.
Edge -- I don't know since I'm outright refusing to use Windows 10 until they fix a few major issues such as: stop using it as an advertising platform to push people to buy Microsoft Products, stop having it 'call home' with my usage details, and quit trying to force me to use Microsoft Software for everything by constantly changing my file associations to point to their software whenever it 'thinks' (yeah sure) there is a problem with my file associations. If someone else out there knows how feel free to add it in a comment on this post.