[Raleigh]

I've made several fake cans for radios that are missing their can caps. I've usually been able to find PVC pipe about the right diameter and cut it off the right length. Any fairly stiff flat plastic will do for a top. Just cut it as perfectly round as you can, glue it to the top, and finish it with sandpaper, a file, an Xacto or whatever it takes.

Spray it with aluminum paint from the hardware store.

Some of the guys at my local ACE hardware store are interested in my radio projects, so they're willing to cut the PVC for me from scrap and sell me just the short piece I need. Their cut is straighter than one I could make with a hand saw.

If you are trying to fake one with the large nut on the bottom, you could just glue the painted fake cap to the chassis. If you don't want to glue it to the chassis, maybe you could glue some concentric PVC pipe pieces into the bottom side to reduce the diameter (below the chassis where it won't be seen) and then glue in a bolt so it would be like the orignal. With washers and a nut, you can probably find a way to hold it in.

The fake capacitors I've made have been realistic enough to pass a casual inspection. I've usually put the replacement electrolytic inside the fake can, but you could just mount it underneath, like Terry said.

Unfortunately the slender, single value caps that Philco used just before the war had a rolled perimeter around the top, so putting a flat top on, like I did, wouldn't look exactly right. It might be better than to have an empty hole, though.