Download of Plot Spooler 3.13.1220.15 was on the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The actual developer of the free software is Dumsoft.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The software lies within System Utilities, more precisely Automation.
From the developer:
The Plot Spooler applications allow you to queue plot jobs so than can be plotted in one operation without the need to manually send each job through to the plotter. Includes advanced features such as a quick plot previewer to assist with finding and plotting the correct job, options to pause for delays between sending jobs and to delay after a group of plots to assist with plot nesting (stacking). The Plot Spooler application is provided free.
You may want to check out more software, such as Spool-Explorer IV, Print Spooler Fix Utility or LPR Spooler for Windows, which might be similar to Plot Spooler.