For the sake of design simplicity and ease of assembly, the mop module is broken up in to two main parts based on the module base design.  The front of the module (the 150mm^2 square) is devoted almost entirely to the water storage tank and the rear is where all of the electronics and mechanics are.

The picture above is a failed print of the front part of the mop module.  Rather than just tossing this piece, I ended up using it to test out the waterproofing capability of the XTC-3D print sealant.  It ended up working perfectly.

Despite the failed nature of the above print, it still demonstrates the main sections of the front of the mop module.  The main water tank is bounded by two walls, the left in the picture being the back wall of the water tank and the right wall being the front.  The small gap between two walls on the right side of the picture is the location of some holes in the base of the module that will allow for the water to be evenly dripped onto the floor.

This bottom view of the part gives  a better view of the holes

Two holes in the back of the water tank provide an input to the pumps.  Because combining electronics and water is a big no no, I added some holes in the bottom of the module so that any leaks around these holes would drip onto the floor rather than flooding the electronics section.

This is the back of the mop module where all of the magic happens.  The holes in the bottom provide mounting points for the two motors that will drive the pumps.

The two pillars in the very back provide a point to mount the base of the pump.

The two, dual-shaft motors have one output shaft extending out of bottom that will be connected to the scrubber and one extending upwards that will be driving the pump.

A picture of the downwards facing shafts.

The above picture shows the back of the module with all of the hardware mounted.  Unfortunately, I didn’t give enough space for bolt heads that hold the motor in place.  The pumps can’t pushed down as far as I intended and so they don’t line up with the holes I left in the mounting pillars.  Luckily the mounts are sturdy enough to mostly hold the pumps in place and so I don’t need to mount them for testing purposes.

These are the two halves the the scrubber that will hold the microfiber cloth that will be used to scrub the floor and soak up excess water.  The two halves are made to be pressed together with the cloth sandwiched in between them.

This picture shows the cloth and scrubber assembled.  I underestimated the thickness of the cloth, so two won’t currently fit side by side.  I’ll need to either make the cloth smaller or move the scrubbers farther apart.

Above is an overall picture with all of the pieces put together.