One way would be to draw the parts, edit as necessary, then stitch together:
First a circle, so one can get a semi-circle:
(it will help to have the grid set up so that things line up/snap nicely)
Node Edit:
right-click:
Cut Vector:
d to delete the current selection (or use the right-click menu):
select the remaining node:
d
Done
Draw in geometry as desired using the Polyline tool:
Done
Select:
copy-paste or Duplicate:
mirror along the vertical axis:
Drag into position:
Select all and copy-paste:
Drag into position:
repeat as desired, then select all:
and Join Vectors to get a single object:
