Just a simple little filament guide... I had some trouble with the current popular ones on Thingiverse due to my BMG Extruder. Its placement is situated slightly further back than stock. Due to this the filament was scraping on the sides of the guide. This design prevents this by simply being aligned correctly.
This part may just work correctly in my specific circumstance but I may as well share just in case. ;)
The bearing end has a 3mm hole with a captive M3 Nut. Its designed for a GT2 belt idler as it has sides to prevent the filament falling off.
Such a bearing can be ordered here extremely cheaply:
Side note: The STP file is provided for anyone who would like to make changes.