I found a ''Generation 1'' Optimus Prime model and made it 3D printable. It had multiple shells and some errors. The feet are still not level so don't know if it will stand, I oriented it and scaled it.

If you print it please upload some pictures here, enjoy the model!

Source of the design: https://sketchfab.com/3d-models/optimus-prime-718071da966b4457b3b24c0f29e6885e

Source of the fan art/background image: https://www.tfw2005.com/boards/threads/g1-cartoon-backgrounds-to-use-for-backdrops-part-one.980469/

https://www.3dwp.nl