This is a SD-Card holder which I designed for my Prusa Bear upgrade.
Slide it in the rail before adding the endcaps, if needed it can be secured by a M5 allen screw (same type as for the endcaps).
I've printed it with custom supports using Simplify3D but also added a second file with integrated supports choose as you like.
Sorry for the "stringiness", I had accidently chossen a wrong profile and printed it a bit too hot. ;)
Das Filament PETG