Interesting.
I've actually done this myself when I couldn't find an exact replacement capacitor. I took apart the defective one carefully and mounted a modern close equivalent inside and resembled it into the circuit. It then worked perfectly. I did it because of the capacitor's form factor and mounting hardware.
I've also done this for an old capacitor which had triple caps inside one case. Since I couldn't find a replacement, I fit 3 equivalents inside, sealed it up again and voila!
But, I wasn't selling them.
I suppose someday, when someone acquires my antique and needs to replace the capacitor, they might be astonished.
Many moons ago, I had an old car in which the rectifier tube died in the tube radio. I replaced it with a solid state diode. Worked great! No one would be the wiser until they opened the case.
Al