Firstly, let's explode the myth that lead tubing is dangerous.  All
things in this world are dangerous if used incorrectly.  Lead tubing
is the _only_ tubing that can be used in certain applications in some
pianos and orchestrions.  This is where tubing is routed around tight
corners, especially down the back of stacks and around the playing
action.  Neoprene or silicone tubing just cannot be used here due to
its propensity to straighten out rather than hold its shape.  Also,
the close bunching of tubes in places will lead to flexible tubes being
compressed flat whereas lead will sit neatly together without any
impediment to the airflow.

There are just a few simple precautions to be taken when working with
lead.  With old lead to be reused, never clear the tube by sucking!
There will always be a small amount of oxide inside the tube so just
blow this out and vacuum up straight away.  When handling any lead just
wash your hands immediately afterwards and refrain from eating and
drinking in the workshop.  Simple.

Lead tubing can be bought from OSI in USA, http://www.organsupply.com/ 
and from Laukhuff in Germany, http://www.laukhuff.de/en 

I find lead tubing a joy to use and the end result always looks far
neater than using neoprene or silicone.  You will also need to learn
how to make and use burnt shellac as nothing else should be used to fix
led tubing into wooden holes.  The MMD archives will help here.

Nicholas Simons, GB