I made a keychain with a hidden loop. With a layer height of 0.2mm you should set up a pause at layer 38 and put the ring in. I used this Keychain: https://www.aliexpress.com/item/1005003803735916.html If you don't have a 3D printer, I sell it on Etsy: https://www.mikebayer3d.etsy.com The original design is from DrLex https://www.thingiverse.com/thing:2738211 https://github.com/DrLex0/print3D-FlexiRex Follow me on social media: [Facebook](https://www.facebook.com/Mike-Bayer-3D-Druckservice-108801391734722 "Facebook") [Instagram](https://www.instagram.com/mikebayer3d/ "Instagram") [Pinterest](https://www.pinterest.de/mikebayer3ddruckservice/ "Pinterest") [Twitter](https://twitter.com/MikeBayer3D "Twitter") [Printables](https://www.printables.com/social/244886-mike/prints "Printables") [Cults3D](https://cults3d.com/en/users/mrmbmrmb/creations "Cults3D") [Thingiverse](https://www.thingiverse.com/mrmbmrmb/designs "Thingiverse") etsy Shop: [etsy](https://www.mikebayer3d.etsy.com "etsy")