I go to a fair amount of old car shows during the fair weather season, and I suggest you try your hand at that venue. Rent a vendor's spot, set up a table with some samples of your work, and have some business cards printed. There's more than one guy that does striping or airbrush work that earns a few bucks on a weekend.
Things to brush or stripe; mailboxes, toilet seat covers, old hubcaps as clocks. You could even do small flat panels with classic characters on them. (Betty Boop, Taz, or try WW2 nose art style paintings.)
If you're into bikes, a guy can make some decent coin there, too. Bikes can be done in a short amount of time, giving you a good labor-to-profit margin.
By chance, do you use One-shot for paints?
Roger