Fred, there is no minimum but I might add it does not take much. Some have just been around C/L scale for a time and has added to its glory,.
A nominee for HOF should be someone with some time involved in c/l scale; builder, designer, publishing, columnist, competitor, scale committee's, judge and just there overall contribution to the c/l scale discipline. Naturally one would not have all these credentials but would need some of them, there biography will tell the board what we need for there induction. Placing in contest, nationals and international is not a must but it will add to there list for consideration. Nominee should be endorsed by someone other than themselves.
Blessings
Allen