The burner Make the burner out of a copper plumbing cap of any convenient size. The big hole is for the wick. This acts as a vent and is important. Now solder the pipe cap to the floor so that the wick hole is directly beneath the coil. Make sure you have a good solder joint all around.
Soft solder is fine.
Cut and fit some fiberglass wick material, and you're done with the basic unit. The rest is up to you. The rest You may find that the slightest breeze affects the flame and, thus, the running characteristics of the boat. One boat I saw has a dummy vertical boiler that encloses both the flame and the pop-pop motor. It seemed to work pretty well.