Wide attachment at a 45 degree angle for cleaning the stairs. Added thickness to the attachment pipe to ensure good bed contact area. Printed with no supports.
Edit: the attachment diameter is about 3.5-4mm too wide on my Hoover Windtunnel 3. A little duct tape makes for a great temporary solution though.
I'm designing an attachment with a 200mm wide mouth, which I'm planning on uploading as a remix.