On Wed, 6 Jul 2022, Henning Hraban Ramm via ntg-context wrote:

> Hi, I’m trying to understand MetaPost better.
> 
> I’d like to draw a fat line that’s cut at its end points.

You mean like linecap = butt?

\startMPpage[offset=5mm]
  path p;

  p := origin -- (7cm,0);
  interim  linecap := butt;
  draw p withpen pencircle scaled 5mm;

  p := p shifted (0,2cm);
  interim  linecap := rounded;
  draw p withpen pencircle scaled 5mm;

  p := p shifted (0,2cm);
  interim  linecap := squared;
  draw p withpen pencircle scaled 5mm;

\stopMPpage

> I learned, “cutdraw” should do the trick, but I get a parallelogram 
> instead of a rectangle.

Seems to be something weird with pensquare:

\startMPpage[offset=5mm]
  path p;

  p := origin -- (7cm,0);
  % interim  linecap := butt;
  cutdraw p withpen pensquare scaled 5mm;

  p := p shifted (0,2cm);
  interim  linecap := rounded;
  draw p withpen pensquare scaled 5mm;

  p := p shifted (0,2cm);
  interim  linecap := squared;
  draw p withpen pensquare scaled 5mm;

\stopMPpage

Aditya