John, Sorry if I sounded dismissive, it wasn't meant to be offensive, but rather hopefully informative.
You were referring to a small part, that could be done on the bench in a jam jar, 1/4 teaspoon of soda and either a car battery charger or an old mobile phone charger
(but this should be done outside because of the explosive hydrogen gas produced, so room really doesn't come into it for most people)
Smaller parts should take less time so it might be done in an hour.
But rather than spend £12, a 26p jar of vinegar would achieve exactly the same result and come with it's own jar. I also gave some other options.
I have over the years had the need to de-rust many parts, and as such tried most methods inc an awful lot of propriety products. I have even imported them from the US at great cost.
Of them all just one product shone above all the rest, (in fact the rest gave pretty mediocre results in my opinion) a product called "Metal Ready" from the US but don't expect it to be cheap as it comes in gallons. They all share one thing in common, they contain acids of some description that does the work. The rest of the goo is just a carrier.
The truth is vinegar or builders cement mixer cleaner are not only cheap but is also just about as effective. cement cleaner esp so. Heck it the same acid as the propriety products use and normally at a 16% concentration so it's stronger.
I have never tried electrolysis to remove rust before, but I have to say it beats all of the other products hands down. There is no question about that in my mind now that I have tried it for myself.
If someone can't rig together a small vat with the necessary parts then they really are not trying very hard are they?
Washing up bowl, water, washing powder, cleaning agent or even salt, (even just plain water will work, it'll just take longer), a piece of scrap metal, small power source being a car charger, phone charger or even a battery even if it's out of your car.
It's so simple I cannot imagine anyone here does not have this stuff to hand or can't pop to the store tomorrow to fill the missing pieces of the jigsaw.
Most people can set this up without spending a penny, like I did....it's not hard.
But if you'd rather make someone else rich then that's your prerogative, I really can't afford to cos I'm poor ......