Custom Paint - Workshop specials.

I'd love to say there are loads of other equally good products but we don't use them here so I'd not be giving legitimate advice. The Starchem one is the only one I can say totally works... I used it today.

If you found out what the active ingredient were I'm sure you could get hold of a similar product in a smaller quantity.

Lots of shed dwellers claim that Nitromors doesn't do the job any more.
I've used it recently and although I'm not a chemist, it is quite clearly less effective than it used to be. Apparently there's a powder you can buy on Amazon to mix with Nitromors to give it the strength it needs but you'll need to do a bit of googling to find out the specifics. That would be a good way to get a smaller amount.