Thanks for the info. I like the Alex Meade website.
Harbor Freight has a motorcycle wheel balance outfit for $40. It has a shaft, 2 cones and a stand with bearings. Wait for the discount coupons prior to purchasing anything. I prefer to purchase domestic stuff when available.
Looks like suitable alum. bar stock can be purchased online for maybe $10/ft. An hour with a lathe could produce quite a few cones, etc.
IIRC Doug Fattic has collected some examples of one-off fixtures with steel cones in his shop/classroom.
Seems like something with a smaller central bore could be adapted to a jig made from 80/20 stock.

I intend to produce no more than a few frames in my lifetime. Low-cost fixtures and workarounds are OK for my negligible production.

My Craigslist O2 Concentrator (indoors and dry) and barbeque propane tank ( stored outdoors ) keep costs low and neighbors are less worried.