Seventy years ago this month, the June 1945 issue of Popular Mechanics carried the plans for the two crystal sets shown here. As the article points out, crystal sets can come in two varieties. The simplest set has little selectivity, and is suitable only for tuning in the one strongest station in a given area. For more variety, a more complex set with more selectivity is required. The magazine showed two sets, one in each category.
The simple set had its coil and all of the other parts mounted on a plastic drinking cup. The more selective set contained two variable condensers, both salvaged from old broadcast radios. Complete crystal detectors could be purchased for about 25 cents, or the builder could make one with a piece of galena. Thus, even with wartime parts shortages, most hobbyists would be able to scavenge together the needed parts.
For those wishing to replicate one of these designs today, I have ideas for finding parts on my crystal set parts page.