Customizable cable duct

It's a simple customizable cable duct / guide with matching top cover. I needed some custom cable duct to organize wires in an electronics box and couldn't find one that fitted exactly.

Added two example files:
- Duct with 70x10x10 mm in size (from first version script)
- Duct with 100x15x15 mm in size, with text, equal width of cover and duct

It's also on GitHub: https://github.com/RealNagus/CustomizableCableDuct