Source Files for 3D Roller Blind Adaptors published here: https://www.thingiverse.com/thing:4284569
These allow me to use the BOFU EY2512-1.5/28 roller blind motors with my blinds. I'm publishing the source files here as I'm sure others will have different blinds again.
Just print the end and inner for your blind, put them on the motor and then insert the motor into your blind. I have them as a fairly tight fit, so try to be careful as you push the motor in. When you get to the end, you'll need to rotate so it lines up with the inner tube before the final push to settle it all in place.