We unplugged my "Heeksatrol" computer from the Bridgeport Series 1 and replaced it with a PC running LinuxCNC. In less than a day we had it moving the 3 axes, with very little work by us.
We copied some code to make LinuxCNC ask us to press a button to continue on a tool change:

 loadusr -W hal_manualtoolchange
 net tool-change iocontrol.0.tool-change => hal_manualtoolchange.change
 net tool-changed iocontrol.0.tool-changed <= hal_manualtoolchange.changed
 net tool-number iocontrol.0.tool-prep-number => hal_manualtoolchange.number
 net tool-prepare-loopback iocontrol.0.tool-prepare => iocontrol.0.tool-prepared

But we didn't work out how to make it retract up to our limit switch on a tool change, yet. 

The stamp we made was used today. The resulting piece of silver looks good. They put it through the rollers on a too tight setting, though, and squished the stamp. So we'll have to make another.

 

Sodium Chloride solution 2.2V 5A, 2 hours, Mild Steel. 106mm x 55mm
John and I used a bigger tank for our electro etching. We also had a fish tank pump making bubbles of air come up from the bottom. ( We made some holes in a plastic pipe and  blocked the end )

We also tried writing on a stainless steel spoon with a CD marker and doing it for 20mins.