The 3D files for the linear actuator used in this project can be downloaded by clicking the button below.
Once the supports are removed, your bracket should look like this.
Some sandpaper may be useful to smooth out the slot where the extender arm will fit.
The extender arm should be printed with high infill to give it strength. If your slicer allows, printing with a negative dimensional adjustment (-0.02mm or -0.04mm) will help it slide smoothly in the bracket.
Install the circular servo motor attachment inside the drive gear.
A little bit of super glue or E6000 glue works well for this.
Once smoothed and assembled, your linear servo actuator assembly should look like this.