Once again I didn't get a whole lot done, but this needed doing.
The original plastic I was using for the inner part of my PSIs was showing LED hot spots, so I went to Home Depot a couple of weeks ago and purchased a new plastic sheet that is bumpy on one side and flat on the other. There is a second piece of plastic over the hole in the dome to help further redirect the offending photons.
The new plastic does seem to work somewhat better. It's not perfect, but nothing I do ever is.