This is an outside corner diffuser elbow for the 45° LED strip mounting channel. For whatever reason, at this time they do not make one for turning outside corners.
This can be purchased from my Etsy shop at https://www.etsy.com/shop/Stacked3D by sending a message.
Added a 120° for a roof gable top corner I needed.
LED_Strip_Channel_120.stl | 435.5KB | |
LED_Strip_Channel_90.stl | 165.1KB | |
LED_Strip_Channel_90_inside.stl | 425.2KB |