How to fix small radiator access "end caps?"

Hi -

I have a hot water radiator system in my home. In my laundry room I have a very small radiator - 4'1" long, 9" tall and about 5" off the floor. This looks to be original to the house - about 1940. I've posted some pictures below. Both "end caps" of this radiator are rusted and beat up and are easily removed to show the bleed valve, etc. These end caps once had a metal access door on the front, but those are long gone, and someone screwed a rubber flap onto the front where those access doors once were (black part of the 2nd photo). Questions - 1) Are these access doors still made and, if so, where could I get two? and 2) If they aren't made, any suggestions as to how to repair these and what, maybe, to use instead of rubber flaps? Many thanks!