The Marblatron produces a brilliant pulse of light, signaling the arrival of a metallic ball from the Luminiferous Ether. This ball spirals downward. Mainly this is due to the effects of gravity, amongst other things. Until finally it disappears from whence it came.

https://www.youtube.com/watch?v=5Zvh_fvajl0

The light is generated from a 24 LED Adafruit Neopixel ring. This ring fits neatly in the cap piece, and a ribbon cable runs down through access holes in the riser sections to the base. In the base there is a location for an Arduino Nano that runs the Neopixels and ball sensor. The ball sensor is simply two wires that are at the top of the screw section. These sense when a ball is about to be ejected onto the track as it comes in contact with them. The Arduino then produces a bright pulse of light just before the ball pops out. At other times, the Marblatron simply generates a rotating pulse of yellow light to help gravity do it's work.

Assembly is pretty straight forward. Start out with one "riser" section and go from there. You will need the number of risers +1 "screw" sections and hex connectors. Inside the screw sections, there is a small notch preventing the hex connector from falling down into the hole. This is only on one side of the screw section. This should be towards the top of each screw section. There are three small dimples in the top of each screw section to indicate the side with the internal stops that should be toward the top. A drop a glue here might help also, though was not required to stack four in my case.

You will need two "bearing" shafts. Place these on either end of the assembled screw sections. The bottom one (that fits in the gearbox) has the gear inserted on the bearing shaft first, and then fitted into the bottom screw section. The gear teeth should point downwards. The vertical motor gear mates with the horizontal screw gear. You may need to drill out the motor gear slightly to get it on the motor shaft. It is designed to be a tight fit on the shaft.

The riser sections, gearbox, and riser top attach together with small tabs. These can be tight enough to break the tabs off when disassembling, so you may prefer to sand them down a little to provide a looser fit.

Each riser section requires two sets of rails (4 total). You will also need a couple extra for the ends. The rail sections just snap into the holes in the riser sections. Where two come together, the hole is wide enough to accept the two tabs side-by-side. Each rail has a small female and male tab that align them vertically as well. The female notch should go below the male notch as you work your way up. The male notch in each rail section has a small support built into the model itself. Snap this off prior to assembly so that the rails are flush were they mate together. It can be a bit tricky getting the rails to align. Do not force them too much or they may snap.

Non-printed Parts Required:
The design uses the following 6V 30RPM motor from amazon: http://www.amazon.com/gp/product/B009AQLDSS?psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00

For the "marbles", I used 10mm ball bearing from a bicycle shop (amazon is a good source).

Also some ribbon cable and headers if using the Neopixels, ball sensor, and Arduino, and a 5V 2amp power supply. Of course the Arduino, Neopixel ring, and ball sensor are all optional, if you don't care for the added effect or added complexity.

Arduino:
The marblevator.ino code is attached. For the attached program, the Neopixel ring ties to digital pin 6. The sensor wires connect to digital pin 2 and ground. The Arduino is powered from the 5V supply on pins 29 (gnd) and 30 (Vin). The pull-up is enabled on pin 2, and the ball making electrical contact and pulling pin 2 to ground is what "senses" the ball is present. There aren't any holes in the model for the ball sensor wires. Just drill these to match whatever wire you have laying around. If the wire is thicker, be sure the ball can get up and over it as it comes off the screw. You can test without the top cap in place to ensure things are working.

Neopixels are a bit finicky. If using them in your build, I would suggest adding a small capacitor across the motor terminals to avoid the electrical noise that may cause the Neopixels to flicker. My Neopixels flickered quite vigorously without this. Also, be sure to add the capacitor and resistor on the Neopixel ring. Adafruit recommends this (see their website for details). Skipping this can burn out the first Neopixel from the inrush current when plugging in the supply (don't ask me how I know). If you do burn out the first pixel due to your brazen disregard for reading instructions, it will appear the entire ring no longer works. It is just the first Neopixel that is the problem, however. You can de-solder it, and then apply the digital input to the next one in the chain to get the ring going again, albeit with only 23 pixels :(.

The whole thing runs on a 5V power supply, and draws about 1 amp maximum with all the pixels and motor running. I would suggest a 5V 2 amp supply just to be safe. Be careful not to plug the Arduino into USB for programming without the power supply plugged in, or you may burn up something, since it will try to source the 1 amp from USB through pins 29 and 30.

The printed parts all fit within the 6" x 6" x 6" build volume of my printer (actually a bit smaller), so make sure your printer supports that before starting. I used PLA at 20% infill and fast setting on my printer.

I'll add more instructions and assembly pictures soon...