R7RM-
Thanks for the clarification on my attempt. The only custom collar I've actually used is a piece of iron pipe sawn to the appropriate length.
Like yourself, I use washers and similar items to make collet dies work with cartridges other than their original designation. In my Lee boxes are all sorts of such widgets with tags attached so I know what they're for. Last week I found a thin decorative nut from an electric fixture that slips down over a 218 Bee case to allow use of a Hornet collet die.
--Bob
