Like the OP I used svg2gcode and others. The original pen holder I printed worked but I ended up modifying the design and adding a bronze bushing to hold alignment better and a mount for a microswitch so that the pen holder also functioned as a probe to set the Z position. [2]
In order to be able to change pens I made a little "half crosshair arrow" that I would run the gcode for on each pen change and verify the overlap was the same since it is difficult to align the pens exactly on change.
All of this was done using V2 Smoothieware as the firmware.
[1] https://youtu.be/nJI-yXbHHJA?si=F9bXftj7UEXyuRxa https://youtu.be/ZSP37Kgp7Tc?si=Mn_IKjU9t9zmaOml
Large format pen plotters with up to 8 separate pens were available for different line weights. Color was mostly avoided because the reproduction process of the time was still centered around diazotype[1], or monochromatic ammonium blue printing.
[0]https://piratefsh.github.io/2019/01/07/computer-art-history-...
My HP-7470A is from 1982 and does not have stepper motors, but DC motors and rotary encoders doing closed loop servo control. They move the lightweight paper itself instead of a heavy gantry.
Worth noting that this HP sold printers and atomic clocks, unlike today's HP which sells cheaper printers and subscriptions to them.
They've had this feature out of the box on a few Bambu models for quite a while now. It was part of the H2 series, and the A2L is them expanding it to the cheaper models.
The printers come with software to lay out text/drawings, line up the paper with the overhead camera, and run the job. And it comes with a tacky plate to hold the paper in place while drawing. It's all pretty slick - no need to mess with custom g-code or anything. You use the same process whether you are drawing, using a drag knife, or laser cutting.
I've had a post card based business idea for ages. Can anyone recommend a printer that prints quality postcards? I'm looking for something in the sub $2,000 range. I pulled that number out of thin air so I have no idea of that's a too much or too little.
The print might not fare that well though the post system, though, so maybe it wouldn't be suitable for postcards. But it can be a nice touch.
The printer calibrates, pauses, you attach the pen, press continue, and it'll do the plot without zeroing the Z-axis again.