Simple parametric box and lid

This OpenSCAD file creates a box and a lid that respect a couple of aspects:

- rounded corners and edges favourable for certain printers
- lid with a friction fit
- inner dimension customisable
- wall thickness customisable (defaults to 2 mm)

The STLs are designed to hold a double AA battery holder with enough clearance to allow a KF2510 2-pin connector being pushed through the hole in the lid. See the photo. The connector in turn can hold a LED. (Always use a resistor and don't connect the LED directly to the battery!)