Geeetech filament spool bushing for 20mm center pipe

This is my very first drawing, but I'm a fast learner. It is too small in stl but, I scaled it to fit in slic3r gcode, details below. I drew this up so that my filament spool unwinds just a bit smoother. I did not smooth out the flat ridges because I didn't want it to just keep going on momentum but without really restricting movement. GCODE: I ran it at 15% infill, Slic3r for marlin firmware flavor. I enlarged drawing to 1.1 on x axis and y axis but, kept z axis at 1.0 when I slic3d it so it wo