Primus 2000 Gas bottle filling adapter

I actually joined this site because I was so impressed with the Primus 2000 gas bottle filling adapter featured.

I would like to get in touch with the engineer who posted this adapter that uses the actual blow torch to connect the two bottles.

I have a spare red propane regulator that I would like to convert so that I can also refill the 2000 bottle from a larger one but I have been unable to find out what the burner thread size / type is so that I can purchase the correct drill and tap to make one for myself.

If anyone could let me know I would be most grateful because I am keen to get started .

With best regards

David1

Propane bottle refill kit at Harbor Freight.
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Propane Bottle Refill Kit