Parametric bonsai table

A parametric model for Bonsai display table.

Following parameters can be adjusted with OpenSCAD :
* width: table width in mm (default 90),
* height: table height in mm (default 50),
* depth: table depth in mm (default 90),
* thickness: tabletop thickness in mm (default 2),
* footsize: square feet size in mm (default 10),
* radius: carving radius in mm (default 3),
* hole_offset: carving offset in mm (default 1).

Note: The carving depth is radius - hole_offset and is identical on the top and bottom of the table. With default values, the carving in 2mm deep.