.
,
found as "Arc From Start Circumference End" under the "Polygons" menu.
This function
makes a circle arc given the point of the start of the arc, any point on the
circumference between the start and end, and the point at the end of the arc. The
input points are (1,0,0), (2.5, 1.5, 0), (1, 3, 0).
To make the upper hump of the B, use
the arcCRAA function,
found as "Arc From Center Radius Angle Angle" under the "Polygons" menu.
This function takes an arc
center, radius, and start and end angle to make a circle arc. The input values
are center = (1, 4.5, 0), radius = 1.5, startAngle = -90, endAngle = 90.
.
To make the inner contours of the B, use
the offsetPoly function 
,
found as "Offset Polygon" under the "Polygon Constructions" menu.
It takes any polygon and creates a new version of it that is every where offset by
a given distance. The new polygon is parallel to the original polygon everywhere.
Note this is not a simple global shift of the original. The positive distance offsets
to one side, a negative offsets to the other. All functions in CADZilla that
take objects as input give three options regarding what to do with the input
objects. If the "Consume Original" option is selected, input objects disappear and
become part of the resultant object. They still exist: in the case of the offset
they can be found as part of the offsets "polygons" field. If the "Consume Copy" option
is selected, a copy of the input objects is created and the copies become part of
the resultant object. If the "Consume Link" option is selected, a *link* copy is is
made of the original and the link copy becomes part of the resultant object. Chose
the "Consume Original" if you don't need the input objects for anything else. Chose
"Consume Copy" if you want to keep the input around for other purposes, and you don't
want the resultant object to be related to the input objects you are keeping. Chose
"Consume Link" if you want to use the input in multiple constructions, and you want
them to all be identical. For this offset, "Consume Copy" was used, and the offset
distance was "0.25". And another vertical is drawn for later.
.
The next step is to extend the small offset ends to the vertical line on the right.
To do this use
the extendPoly function 
found as the "Extend Polygons" function under the "Polygon Constructions" menu. This
function extends the ends of exiting polygons to a given boundary. The polygons
are extended by either creating a special extension shape that holds the extended
polygon and generates a single geometry that is extended, or by simply adding a line.
To use this function pick the vertical line on the right and hit the "Start Extending"
button. Then pick the ends of the polygons to extend.
Remove the vertical line and draw two lines to close the two holes in the B.
