[exray]

One trick I read once on a website was to use RTV to make 'gum' washers. There's probably a zillion ways to approach this but visualize filling the end of a pipe of the correct size, popping it out after it dries, trim the height with an xacto knife, drill a hole and voila!

Of course a trip to the hardware store might be easier but this particular chap was in rural South America where some simple things were not available.

-Bill