Hi Bob,

Now,  you’re ready for mass production !

Just kidding, this set is an eye catcher, well done !

I recommend using strong neodymium magnets underneath each cube to make a sturdy construction.

For the ground connection, you can use these magnets for contacts. Some of them have small eyelets where you can attach a wire using a bolt and nut.

Did you use a special earphone ?

I would love to see a circuit build with this set.