Two different kinds of Lucite...House paint and automotive lacquer.
If the Lucite your talking about is the old Dupont Lacquer Lucite, use a virgin thinner, (by virgin I mean not gunwash but real, clean thinner)...You can reduce it to whatever you think will get through your gun and spray right. I haven't shot lacquer in years...but love the stuff...still one of the best shines you can get after a quick cut and buff...Just make sure that you lay down a good sub straight with rust inhibitors, lacquer is porous and rust will start quickly with out proper metal preparation, Epoxy is great, maybe to thick for and expensive for patio furniture, so try some etch and shoot over top...Some of those old lacquers don't shine much unless polished but give it a shot...
If it's house paint Lucite, paint thinner from Home Depot will thin it out.
Hope this helps