Nothing that fancy John, just a piece of fairly longish copper plumbing pipe and something around 3/16" to 1/14" for the air. Get the air pipe a fair way down from the pickup end, say 6", and just solder the two together. You don't have to have a bag, just a length of flex pipe going to the dustbin would do.
Dave, this wet/dry one has a shake out filter, and a float to stop the suck when it gets full of water. I used my old one for sucking out all the slushy mud out of the bottom of a sump drain in the garden, it worked great.
This one will be even better because it is more robust.
John