I created this to allow my vacuum robot to clean the bathroom, without leaving the door open. The Dreame X40 is integrated in Homeassistant, so the door can open automatically when the robot is in the hallway and close again if the robot is back in the dock.

Printing:

Use your preferred settings and filament. No support needed, all holes are already bridged with a sacrificial layer, which can easily be pushed out with the corresponding screws.

Hardware:

• 1x DS51* Servo. (DS5160 - DS51150. Should be available on Aliexpress for ~20€. I used DS51150 because it supports 12V)
• 2x M6 Nut
• For Link_A:
  • 2x M6x15 socket head screw
• For Link_B:
  • 2x M6x25 socket head screw
  • 2x male M6 uniball joints
• 2x M3x10 flat head screw
• 4x M3x ~20 socket head screw (20 - 30mm works)
• 4x M3 Nut
• 2x 4mm thick flat head wood screws (Adjust the length to the thickness of your door)
• 2x Hinge (Just use any cheap hinge from the hardware store print some)
• Servo Controller (I used a D1 mini with ESPHome. I also added a relay on the 12V line to the servo, because the servo will even hold the position actively, after the servo is detached in software)

Assembly:

Cut the lower part of the door in a straight line at a height, so that the robot vacuum can fit comfortably under it. For my Dreame X40 Ultra I chose 15 cm.

Reattach the lower part with the hinges.

Assemble 3d printed parts as described below.

Select the correct mounting position for the fully assembled door opener. The arm should be perfectly vertical if you use Link_A. Link_B allows more tolerance.

The mount on the flap can be attached with glue (e.g. hot melt glue), the upper servo mount maybe also, but I needed to screw it into the door.

Make sure to route the cable to the side of the door hinges. Maybe you want to mirror the servo mount before printing.