I can’t find a tool to enable me to print an envelope with the address used in a letter
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The question sounds a bit as if the OQ hopes for sorcery.
An address “used in a letter” isn’t supposed to be a data source for printing an envelope. In many cases it will even not be sufficiently formatted for the purpose.
You need to use a data source containing your addresses for the creation of the envelopes, and also for the address field of the letter - if any. This is “mail-merge stuff”.
I personally don’t like mail-merge, and don’t actually need it because the number of letters I send daily is far below 1 by average meanwile. (I am retired.)
Anyway I still use a thoroughly designed letter template I made many years ago, which even allows for its sender and address frames to be used for the printing of envelopes. To date I never did it, but it was kind of fun to write the needed code. It works for me.
See attachments. You may need to adapt them regarding your environment.