If you have dust extraction that would do nicely for a vacuum hold down.

Not sure if 1/4" ABS will cut very happily at router speeds, it tends to melt, but I think you will probably want router speeds for the other materials :nope:

If you whack a pen down with a solenoid it tends to dent the surface and deposit a blob of ink. The ink carries on down after the pen has stopped.
If you use a soft landing it takes more time. One speed solution is to use joined up writing

I used to be a service engineer working with Houston Instrument vinyl cutters, pen plotters etc. Gives you a rather jaded view if you only get to see them when they go wrong :whistling: