They do stick their heads in the pipes to eat. We have the bucket elevated on a block so the pipe is about even with their backs. We made the bucket feeder when they were around 12 weeks old. We used a standard mason jar chick feeder when they were babies and tried using a rectangular tupperware style container with holes cut in the side when they were a little older. Neither of those worked very well as they were dumped over multiple times a day. We still haven't decided what to use for this years new chicks.
Here are the detailed directions I followed to make the bucket feeder