This is it almost assembled:

Here are the parts:

It even has a filter. I can use a good filter or even a tissue:

Its made from a Sisema Klip ot Breakfast to go container.
So far the costs are $20 for the fan, $5 for the container, $5 for the O2 injector port $5 for the switch and power connector. This fan runs off 12V so I'll just grab a plug pack that is in my box of unloved transformers. The fan should have been much cheaper but it was in the shop I was at.