When I tore out the old boiler that was in this house, then a few yrs. ago I installed them on my faux-bolier that actually is my return air drop for my hot air furnace.
With the price of scrap steel having been so high I would think such an item would be harder to find anywhere.
I saw a picture of a fake cast-iron radiater at a movie studio in England. One guy picked it up and carried it like it weighed almost nothing, a very good job at reproducting the real thing. If a person had one of these it could be hung above the path from the ceiling (as was commonly done, then have it seem to come loose at one end as the 5 pounds of foam and latex swung at them.. then stopped short of coming within range.
Some of the cast iron boiler doors would have the name of the furnace company cast in large letters, then the small "glass" observation window made from izenglass (sp) and a small knob that controlled some small shutter type air vents and of course the noticable hinges and lever to lock it tightly closed were all the main features of such a furnace door. I also saved some old boiler gauges brand new in the box from my Dad's sale, pretty nice "Steam-punk"-ing items, I have used some already on my Fear-Degausser machine.
The older model boilers also has a door down low for shovelling in the coal./taking out the ashes.= three doors total.