Customizable shelf tab

This makes a simple shelf holder made up of a spoke that fits into a drill hole and a tab that holds up a shelf. It is all customizable - just open in customizer and resize for your shelving needs.

This component is part of an open source lab library, by the [Michigan Tech's Open Sustainability Technology Research Group](http://www.appropedia.org/Category:MOST).

For similar see the [Open-Source Lab How to Build Your Own Hardware and Reduce Research Costs](http://www.appropedia.org/Open-s