This build requires rails. The SD9 frame isn't very special, it's just one more option. The frame also comes in a glock mag supporting variant.
https://ctrlpew.com/freemans-sd9-3d-printable-sd9-frame/
https://ctrlpew.com/sd9-glock-mag-conversion-frame/
https://odysee.com/@TheGatalog-PrintableFramesReceivers:9/SD9:9
https://odysee.com/@TheGatalog-PrintableFramesReceivers:9/9mmSD9GlockEditionPistolFrameandDIYRailSystemFreeMenDontAsk:3