The Specialized SL7 stem doesn't come with the stem bat that holds the cables close to the underside of the stem. This design is similar to the OEM design. I found it difficult to affix but once attached it has held up well. I'd definitely recommend the metal OEM part (#S204800003) since it's pretty cheap and probably works a little better.
I printed in PETG at .2mm layer height and 100% infill.
It is designed to be attached with a M5 x 16mm (20mm will work) flat head, countersunk bolt.
The author hasn't provided the model origin yet.