Search:

And... I do buy things from... https://www.aliexpress.com/item/mirror-box-frame-3D-STL-artcam-model-cncn-router-engraving-carving-R005/32781667565.html?spm=a2g0s.13010208.99999999.326.30453c00pR6HRa...

You might try Pinterest, search "grayscale" click once on picture for more of the same type, click again for source. Also ebay, search stl, 3d, cnc. Good luck.