When open, a E26 / E27 Edison base is a shock hazard. It also can let dust dirt moisture and paint in the socket limiting its useful life.

The solution:

3 Different Types of light bulb safety blanks:

Long - Great for long fixtures and is easily removable, has a coin slot for extra grip just in case.

Short - Works for string lights to keep dust, dirt, and moisture out.

Tamper Resistant - Same as short, but keeps little hands out of it, easily removable with a screwdriver.

3 different filament settings:

PLA - Simple to Print - Recommended for indoor or cold climates only, does not have good resistance to direct sunlight.

PETG - Middle Ground - Moderate heat and UV resistance when printed in black.

ASA - Requires Enclosed Printer - UV and Heat resistant for years if not decades.

Safety and Disclaimer:

Make sure power is turned off before removing. Do not use conductive filament such as carbon fiber, or metal infused. These devices are highly resistant to moisture and contaminants, and are better than leaving them open in most cases; but not 100% impervious. Use at own risk, and under advisement of a professional if necessary.