This is my heart keychain.  You have a choice of either design.  One is blank that you can add your own words to in your slicer. Feel free to take the insert concept and add to your own models depending on the keychains you have. keychain inserted mid print.  Its a strong design.  I encourage you to implement this design into your keychain ideas.  I have included the Fusion model for you to modify as you need.  You pause the print just before the closing layer, insert the keychain (small end) then continue the print. With the purchased keychains, its easiest to close the jump ring on the end using two small pairs of pliers.  If printing multiple keychains on a tray, just leave enough space for the chains to lay flat.  Then the small ring is the end that gets put on the print when its paused.  Then continue printing.  Leave enough space for the chains to float below the print surface if your doing multiple on the same plate. Pause is on Layer 32.

Here are the keychains I used, you can also find them for less on Temu. But any keychain with a 3/8" jump ring will work.https://www.amazon.ca/CHRORINE-Keychain-Crafts-Keychains-Supplies/dp/B09H5MZR6L/ref=sr_1_1_sspa?crid=3KT2AIFZ7ENS5&dib=eyJ2IjoiMSJ9.LuoiPRNEFX0S27qJronnMJrXinu_Lxc1FAKrTfuKrTTbdc3ldnvYJBN9rxuy60c5E0gLjZ4ouaQGATYp4Z_wsMuzIkami3nFRBM_7L67sTyZJyNZO8s22jgbY1_aVavZiczxqdBSEzkM__6oI8qSFwA_Fh37hf28ksTh8FAJtHu0v6ipYvFivLH-_uS_VKAzKJD0vYdJ3OefL3oJ5DaG81FsByNtXy6wLHjxJcIPI_ilfCIaXx_bbQYMVVLim174jj7rxxloN2_oaeSbcTlJJTIrMk8rL06AYjE6eZA7BBc.eUwjJKrzdqrL6l3rjSHt3ItjCKHAAqfmr3dYYWb5nUQ&dib_tag=se&keywords=keychains+bulk&qid=1759256273&sprefix=keychains+bulk%2Caps%2C154&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1