I'm pretty-sure they came with the brackets and all the hardware required.

Here's one of the hardware kits that came with my Fathom plastics sets direct from CPR:

IMG_8399_(resized).JPG

Your source is incorrect.

I bought more than one set direct from CPR and they all came with hardware.

Just look at the Fathom topper pictures from the CPR website.

What, do you think I bought these at Home Depot or something?

Just look at the weird fasteners they supplied in the kit. Flat-head screws with highly unusual square socket heads. The 5 screws and nuts to fasten the 5 brackets to the plastics and 5 wood screws to attach them to whatever you want.

I don't even know where you would buy them. I doubt you'll find them at Home Depot or Lowes. I don't have any square Allen wrenches to tighten them either.

Now look at these pictures taken from the CPR website. Notice the screw heads.

It looks like maybe CPR provided them with the first batch of plastics but maybe ran out of them or something. I purchased three sets along with a playfield and a backglass and they all had the hardware. I still have all three toppers.

fathplas01_(resized).jpg
fathplas02_(resized).jpg
fathplas03_(resized).jpg
fathplas04_(resized).jpg

They must have ran out or something or decided not to supply them later on.

I assumed all of them came with the hardware since all three of my plastics sets did. I wasn't aware any hadn't until seeing this thread.

Go to a True Value hardware store. I bet they have the exact brackets and most have a nice selection of "show chrome" screws to choose from. I would probably get "Button Head" or even "Pan Head" screws though. I think they would look better.