Epoxied together the X and Y stage acrylics. It's been a lot of unnecessary extra work to grab too thin sheets. Can't recommend it, but I think it'll work.
Drilled the X and Y stage attachments' holes for fixin' to the ends. Using a dull drill bit to drill aluminium is interesting: Rather than cutting, I had to run it at full speed so that it eventually melted the aluminium. Apart from being extra work, it also meant that there was a rim of molten metal around the hole afterwards, which took a fair amount of dremeling to remove. And my dremel is now stuck with a half-used grinding ball on it, as it has shown its crappiness (it's off-brand) and worn itself to where I cannot remove the bit. Bugger.
Tested the one stepper motor driver that seems to work. The Arduino could talk with it, and the exercise program showed that only one side of the motor connectors works.