Marbles are underrated. They’re very round, roll well, tend to be pretty shiny, and come in all sorts of neat colors. That last characteristic makes them suitable for artwork, like orbicular pixels. In his most ambitious project to date, Engineezy took advantage of those attributes (roundness and colorfulness) to build this amazing machine that automatically produces marble art displays.

Engineezy has made a name for himself with his impressive and often complex mechanical design, and this project certainly fits that bill. It is enormous and the entire thing is basically a stack of fascinating mechanisms. There are mechanisms to separate the marbles by color (there are eight colors), elevator mechanisms to lift the marbles to the top of the sorters, pump mechanisms to move the sorted marbles up, feed mechanisms to drop the appropriate marbles into the displays area columns, and a mechanism to dump all the marbles from the bottom to start the process over.

All of those mechanisms require a whole bunch of motors and drivers, along with several development boards to direct them. The feed mechanisms at the top, for example, operate under the control of an Arduino Nano ESP32. It oversees the movement of the two stepper motors that slide two guides back and forth — a design inspired by IDEX (Independent Dual-Extruder) 3D printers. Those use funnel-like ramps created by two coil springs that adapt to the movement — a rather ingenious idea.

The mechanisms all work in concert to drop the marbles into the display area, creating images of 32×32 pixels (1,024 “pixels” in total) and up to eight colors. The machine can automatically reset itself and then display a new image, so it can keep going indefinitely while spectators watch the intricate dance play out.