I found a 0-10 psi adjustable propane regulator at Home Depot. It was a closeout item with a price of $4.99! I built a circular burner from 5/8" copper tubing and soldered in some "jet burners" from the ubiquitous 23-jet wok burner.
The 23-jet burner is available in natural gas and propane versions. I ordered the propane version from kitchensupplydirect.com (it was on sale for $20.03 a few weeks ago), but they might have sent me the natural gas version. I suspec this might be the case because the burner runs very rich. Take a look:
The yellow tips on the flames show that there is a lot of excess fuel. The flames are jumping off the burners probably because the mixture is too rich to start combustion inside the burner tube.
I ordered some hypodermic tubing from McMaster and made the jets smaller by press-fitting the hypodermic tubing into the existing jets. This changed the jet size from about .023" to .012". Now, the jets seem to burn too lean, and have a very hard time staying lit. The slightest breeze blows the flame out. When the burner was running too rich, it also could be blown out by slight breezes. I think the burners are not designed very well. The original orientation in the 23-jet burner caused a lot of turbulence to be generated -- it positioned the jets to aim into each other's path. This might have been a required design element to prevent the flames from being blown out.
Anyway, I'm considering a different propane burner design. More later.