Sridhar Ayengar wrote:
You could probably beat 100F by building into a 55gal
drum and
designing carefully.
If by "designing carefully" you mean putting a lot
of parallel supercaps
inside the drum, yes.
If you mean designing an actual capacitor yourself out of materials you
machine yourself with resources available to a serious hobbyist, most
likely not. Making high-value capacitors is NOT easy, which is why
capacitors >1F didn't become generally available until the mid-1980s.
Eric