Software for drawing this?

[James1979]

Can you draw a rectangle a bit bigger than it; covert the rectangle to nodes (stroke to path); then select the rectangle, hold shift and select your design and then path -> difference?

You’ll then get a negative. Which may help.

You may have to play with path-> exclusion or difference. There doesn’t seem to be a logic as to which works when.

 

[cardiffrob]

Getting there. It seems to be a bit 'temperamental' in deciding whether it will carry out a function or not. Might be finger trouble, though.