Creating an custom spaced line?

Is it possible to have some kind of custom pen that can draw a specific line type?

For example what I want to do is draw a line that draws a dot or dash exactly every 3.85mm over a length of my choosing, like the existing "Dot" pen but with specific spacing requirements.

Right now - no, custom line types are not supported. This is planned to be improved in upcoming releases.

Thanks, I'll guess I'll cope with adding some lines in manually with the command line with the same length and space over and over relative to the last drawn position.