I might have a project coming up in which I would use a F-can MH ballast. However, I am wondering where I could find a junction box that fits over the end of the ballast, or if there is an appropriate commonly available substitute. This will be a plug-in unit that is not permanently mounted anywhere, nor in a recessed space.

As a side question, does anyone know what these junction boxes are called ?

Maybe a small electrical cabinet (not a junction box, but something like a panel chassis with no knockouts removed) can fit over the entire ballast and all connections

The part number for what you're looking for is Philips Advance PC857. That's the small junction box that clips onto F-can HID ballasts.

Alternately I got creative with a handy box and blank cover once. You have to drill two holes on the bottom to match the holes on the ballast flange, then a 3rd hole on the side with a grommet for the wiring.

@joseph : That is good to know. I'll keep it in mind.

I have since found some on eBay, but at the moment it is a lot of 16. I don't need that many.

Here's a lot of 2  :  https://www.ebay.com/itm/Magnetek-Universal-SB-4-Splice-Box-for-Sign-Ballast-SB4-Junction-Box-Lot-of-2/162140591683  The seller has 5 pairs avail. I just made an offer on one .

Thanks, but they don't ship to Canada. I'm in no hurry, so I'll wait for now.

That sucks ! I'll keep an eye out for you !

Here's a lot of 2  :  https://www.ebay.com/itm/Magnetek-Universal-SB-4-Splice-Box-for-Sign-Ballast-SB4-Junction-Box-Lot-of-2/162140591683  The seller has 5 pairs avail. I just made an offer on one .

Yeah I forgot to mention that the Universal equivalent part number is SB-4. I believe they're pretty much compatible with each other's ballasts. I have a fixture that has a Advance F-can ballast but a Universal junction box.

The seller accepted my offer for $12 for a pair so we'll see how well they fit .

They arrived today and seem pretty decent .