Done! [0] And now it is adorning the teapot's own article. [1] The beautiful thing about Wikipedia is that anyone can contribute. I just used the "Upload file" link at the side [2] and it led me step by step through the upload, so you don't even need to know a thing about Wikitext or the myriad of Commons policy (there was a thing about patents but hopefully it's safe on that front). Btw, I uploaded the first one I found that had an open license and resembled the teapot, [3] and am not that acquainted with 3D models, so if you find a better one, don't hesitate. In the future, please be bold [4] in fixing any deficiencies you find in the Wikipedia projects. :)
[0]: https://commons.wikimedia.org/wiki/File:Utah_teapot_(solid)....
[1]: https://en.wikipedia.org/wiki/Utah_teapot#3D_printing
[2]: https://commons.wikimedia.org/wiki/Special:UploadWizard
[3]: https://www.thingiverse.com/thing:852078
[4]: https://en.wikipedia.org/wiki/Wikipedia:Be_bold