Today I covered the paint booth I had previously made, with some plastic sheet - top and sides, with overlapping sheets at the front. As yet I have no way of knowing how practical this set-up will be.
* Subsequent note:
I replaced the polythene a couple of times during the build. Over time, it got covered in paint, then started to flake off as I was spraying, which did not help the quality of the paint finish ;-) *