In my unofficial attempt at the Picasso Design Challenge I have made some progress and I now have two motor units fixed to the display screen. I did have some problems in drilling the acrylic sheet used to make the holder for the display as it is very brittle. I cracked both of the back sheets that make up the four layer holder, in three different places. I thought I had placed the sheets onto a stable flat surface before I started drilling, but unfortunately I forgot that I was resting the display on the heads of the four screws used to hold it all together, so of course when drilling between two of these supporting screw heads the acrylic would bend slightly. When the drill broke through the bottom of the second sheet, the bending was enough to promote crack growth so it kept snapping. It took me three attempts to work this out, but afterwards I managed to avoid any further snapping or cracks. It is not too much of a problem functionally as I have now glued everything together. It is just irritating - I should know better.
I plan to add four motor units to the display, one at each corner, but unfortunately I did not have enough motors so I had to order motor. While I was waiting for the extra motors to come I decided to just 3D print some supports for the two corners that did not have motor. I managed one and then my 3D printer also choose this time to run out of plastic spool so the video below just shows two motors and one support.
The system is just about working and with the two step motors powered to move forward the whole system does actually move. The step motors I used are small but they are also incredibly low power and have virtually no turning torque what so ever. They are just feeble. With only one motor if I added the battery pack to the display it just stopped moving. With two motor units it just about keeps going. I am hoping that with four units it will be acceptable. The system is moving slowly at the moment but that is the plan, so that it can display a magnified image of the Picasso painting that it is covering. Once I have more spool for my 3D printer and four motor units added I will also see about implementing the ability to turn as well as move forward.
The Raspberry Pi 3B+ starter kit and the camera V2 have been ordered so I will also soon (he said optimistically) be able to start displaying images on the display. Then it will be almost finished!