Carabiner
grabcad
You mentioned that you can't recall the specific brand of the carabiner you once used, but managed to reconstruct its design in Solidworks for multiple purposes. If it proves useful for any of your projects, feel free to reach out!
Download Model from grabcad
With this file you will be able to print Carabiner with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Carabiner.