Quantity   Component name
1 × Picaxe Microcontroller A sturdy PIC based micro that will gladly take any amount of back EMF you throw at it.
1 × L298 based board I'll open the design as soon as it doesn't require extra parts soldered onto the footprint.
3 × Limit Switches Using limit switches means that the printer doesn't need any firmware changes - just add a bit of gcode at the end of your print.
1 × Gear motor Possibly with metal gears. I tried to print this, but it's too flimsy.
1 × Sweeper blade I'm using a piece of blank PCB; a butter knife also works well.
1 × Traveling nut and axle You'll have to print a blade holder, and add a spring.