I spent a lot of yesterday generating patterns for the table to run at the Milwaukee MakerFaire.  I ended up with about 30 different patterns and put them together into one gcode file.  It takes 2-3 hours for the entire sequence to run (at 500 mm/sec) before the patterns start repeating.  I put 6 copies of the sequence into the file, so I should be able to leave it running unattended at the MakerFaire.  I added a 60 second pause after each pattern is complete so people could admire it before the table starts overwriting it with a new one.  

Someone at the Makerspace pointed out that when the machine stops running for 1 minute, a lot of people will walk away, and then when it starts running again, a new crowd will be able to get a good look at it.

I installed some COB LEDs, blue on one side and red on the other.  Unfortunately, after about 10 minutes the red ones ran so hot they started burning up.  I'll be shopping for more LEDs tomorrow.

I also tried running with a 15 mm ball instead of the 1" ball I was using.  It seems to go all the way to the bottom of the sand and leaves narrower tracks so the patterns appear sharper.  Here are a few more teasers:

15 mm ball on sand table from Mark Rehorst on Vimeo.

circles with 25 mm bal at 500 mm/sec from Mark Rehorst on Vimeo.

Some of the nicest effects come from the patterns overwriting each other, especially when there are gaps between the lines in the new pattern.