Hello!
I've had a friend at my previous work who used to do very good photoetch at home. Having him was a reason why I never started trying to do my own. But when I was studying, I have successfully made some home made printed circuit boards, and this can be done fairly easily. The etching solution isn't very toxic.
There are bacically two problems when making PE parts. One is a nice clean mask - a sheet in which some fields are very black and some are transparent. Those fields allow the photo-sensitive emulsion to harden, and this way they decide what parts of the copper sheets stay and which are etched away. The real pros, like my friend at work use two such masks, one for each side of the sheet metal. Those masks have to be aligned well.
Second problem when etching from two sides is the etching itself - it has to be even across the whole sheet. Normally, when etching the center of the sheet metal gets eaten away faster than at the edges - this could ruin your sheet. To prevent that the etching solution has to be constantly mixed and held at a certain temperature.
So - sounds complicated and I doubt if you can get a perfect PE sheet on your first try, but definitely can be done at home.
Good luck and have a nice day
Paweł