Talk to whoever is running this at your church and see about making that happen...oddly enough they might support this.
This could be exactly what the boy needs, someone to look up to and learn from. Think mentoring...
I've helped build one. I have a pic that I will post.
All oak construction. 4.5" hole saw used to cut 1" or 3/4" thick plugs. Drilled a 1" hole through the middle then. Took a piece of 1" all thread and put a nut and flat washer on the bottom placed however many plugs you need for...