Seance is a tool for talking to CNC machines that speak HPGL (e.g. some laser cutters). The current state of this tool is very much work-in-progress.
You will need the usblp kernel module loaded.
Add your user to the lp group.
Seance relies on there being a printer server (e.g. CUPS) connected to the laser cutter. This can be set up on a Pi by building and installing the ouija package in this repository. This will set up CUPS and create a user called planchette that is a member of the lpadmin group. After installing the ouija package, a password can be set on this user to allow it to access the CUPS admin interface.
The ouija package can be built by running build-ouija-deb.sh, assuming you have dpkg installed.