To get a good even coating of enamel I've elected to spray wet-process enamel onto the ellipses. Here's my wet backed spray booth...

Yes, it's an old dishwasher!

The water is pumped around from the base to the top of the booth and runs down the white slope a the back. The dishwasher's waste-out pump was still working so I use this to empty the water from the spraybooth into a bucket at the side. It's all a bit improvised I know but it was cheaper than buying a commercial version.

A ventilator pulls the air through and under the small gap at the bottom of the slope.

The ventilation pushes the air through into a filter sock at the back:

The sock is made out of an old curtain and, as I found later, isn't that effective.

I later modified the filter system to use a commercial sock filter and some HEPA filter material between the booth and the ventilator.