I have been thinking what to do when you have an O2 tank that is near empty, but you don't want to give it back to the O2 provider yet because it still has some O2 left? Now you have a full tank, but want to finish off the almost empty tank too.

I decided to make a "Y" adapter to combine O2 from the near empty tank with a full one, to squeeze the last bit of O2 from it. I didn't want it to cost money, so this is what I made (yeah, there are more elequent ways for doing this, but it didn't cost anything).

Things you will need:
3 O2 tubes cut off from the useless canullas the O2 company provided.
1 air-tight empty verapamil bottle from CVS
1 male to male O2 tube fitting

I drilled holes for each of the 3 tubes in the verapamil bottle. The holes need to be a just a little smaller than the tubing, so air doesn't leak. Forced the tubing into the holes, and the tubing forms itself to the hole shape so it doesn't leak.

This is what the "Y" adapter looks like: