My dad bought me a Knight Kit crystal radio for my tenth birthday. I assembled it myself, without help, in a weekend. Probably the most tedious part of the job was winding the huge coil on what looked like a thick toilet paper roll. I then had to lacquer it, and waiting for the lacquer to dry was the worst part. Like all crystal radios, this one operated without batteries and had a minimum of parts.
Luckily, we lived in Chicago at the time, and there were several very strong (50,000 watt) AM radio stations with nearby transmitters, so it worked really well. The reception quality was good, with none of the annoying hum that came from a standard AC operated radio. Furthermore, there were no telltale pilot lights to alert my sister or parents that I was listening to “Yours Truly, Johnny Dollar” or “Dragnet” or “Philip Marlowe” or “Sherlock Holmes” or any other great old time radio detectives well past my bedtime.