Gridfinity Customizable Container

Customizable #gridfinity basic container for Zach Freedman's [gridfinity system](https://youtu.be/ra_9zU-mnl8)

The OpenScad that drives this is a minor modification of [vector76'es original](https://github.com/vector76/gridfinity_openscad), basically just putting it all in one file and making the configuration a bit easier.

These containers differ from Zach Freedman's containers in that:

* Holes for magnets are optional
* The shelf for a label is optional
* The finger slide at the bottom is optional
* Magnet holes end in a cone, reducing issues with sagging over the magnet holes
* Magnet holes are sized to 6.1mm so a 6mm magnet should press-fit into the hole without needing glue (you can tune this in the customizer)

Attached STL files are examples, you should open in customizer to create your own