- The 45° Rule: In general, 3D printers are restricted to overhangs that are under 45°. This allows for enough material to be present under the new extrusion and helps to prevent drooping.
- Peaked circles: If you need to create a circular feature that is perpendicular to the build platform, taper the top of the circle with two tangential lines so that the 45° rule is not broken.
Support structure: Many slicing engines will detect overhangs and can generate a brittle support structure that provides support for overhangs over 45°. This is a nice feature to use, especially when overhangs are unavoidable, but usually uses a ton of filament in the process.
Check out Makerbot Thingiverse for models and design ideas for your next project. Their friendly community has a ton of 3D printer compatible models to share.