There are ways of doing this with plugins or Custom Functions, but if you want to avoid any of that, then you can use a Value List defined to list related field values, and then a calculation to list those value list items, and substituting the list's carriage returns with commas.... Sounds a bit convoluted, but really quite simple...
See attached file which demonstrates this technique :-)
Note that the calculation which displays the list of unique artists is UNSTORED, which is necessary for this to work.
artworks.fmp12.zip 69.0 K
Thanks skywillmott, that worked no problem. A very nice calculation in your example.
Seeing my list of artists makes me realise I have to delete trailing spaces in all my records. I saw there is a trim(text) function, so I need to learn how to use the scrips part of Filemaker to do that for all existing records.