Here's a thing I cooked up recently.

I had a set of Cornish Doublepipes but I really wanted something that uses Scottish fingering.

So I got two Gibson practice chanters and plugged some of the holes so that there's one chanter for each hand.

The great thing about ordinary Highland Bagpipe fingering is that whenver one hand is fingering a melody note the other hand is in effect fingering Low A. So with this doublepipe I can play any ordinary bagpipe tune using ordinary bagpipe fingering and an constant Low A happens automatically, what's called a "virtual drone".

But, at will, you can play harmonies simply by playing a note with the other hand that harmonises with the melody note.

Here's a video I did the other day demonstrating this thing:

http://www.youtube.com/watch?v=m4lw8-3Jf9w

The first time through that part of that jig there's a fixed A drone under the melody, but on the repeat I'm holding open long C#s and Ds to make a simple harmony.