A beautiful question, which, however, doesn't seem to be treated fully by historians; at least I haven't tracked it in the question's way. So I'll try to give an aspect.

In most essays I've looked, the opinion is the aforementioned one by you: that craftsmen, like painters and sculptors, didn't have as patron or protective deity some Muse [check eg. Burford(1) & Tanner(2)]. However, the topic doesn't seem 100% clear; maybe cause of generalizations or parallelisms, the latter noted in older essays, that however are based on different words & will be seen towards the end.

In any case, I haven't tracked some approach by any historian on this very question. So let's see some main sources and the possible conclusions:

The Muses seem to be mentioned already by Homer in the 8th c BCE with an inspirational attribute for poetry, eg. start of Odyssey. Homer also is mentioning them as nine without names, placing them singing with sweet voices [Od. 24.60]. Hesiod of the 7th c. BCE is giving a more descriptive aspect. Here they are daughters of Zeus & titanida Mnemosene [Hes. Th. 53-54]; just to underline here that the name Mnemosene stands for 'memory'. While he is also mentioning that all nine were of similar thinking and had the song/singing in their chests [='ἀοιδὴ'] [Hes. Th. 60-61]. This music feature is repeated and in later, theatrical mainly, works. There's also a mythical music contest-bet story with painful consequences for the loser [a theme more usual with Apollo]; this time between Muses and Thamyris, the best guitar-minstrel of his time. Of course Muses won [Apollodorus 1.3.3].

Centuries later Diodorus Siculus [1st c BCE] is giving his own narrative [Diod. 4.7]: inter alia he's mentioning that to each Muse were ascribed by men the 'familiar attitudes of the occupations around music'. Here's a problem with the word that it's translated as 'music' [=μουσική], cause it's derived by the same word Muse, and though it ended meaning as the music we know today, here it isn't certain if it means 'music' or 'any art protected by Muses'. Nevertheless Diodorus continues with the etymology of the name Muse; he connects it with the verb 'μυεῖν' [=initiate, teach] justifying it on Muses' useful teachings. And even if this etymology isn't supported today [though I've read some recent with similar meanings], it demonstrates I think the ancient general belief. Diodorus at two more instances mentions the really noteworthy education of Muses [Diod. 4.4.3 & 4.5.4].

And now how easily could this teaching-feature be connected with the name of their mother Memory [Mnemosene]?

This connection is also noted later by Plutarch [1st-2nd c CE], mentioning that Muses in some places are called Memories [Mor. 743d]. And he actually relates directly the Muses with the meaning of every science and art [Mor. 744 c-f]; specifically speaking of 'the sciences and arts/crafts accomplished by logos', where this logos is speech/word but logic, too [='τὰς διὰ λόγου περαινομένας ἐπιστήμας καὶ τέχνας']. At least he is giving it as an aspect, while it shouldn't be misunderstood as a given monopoly to Muses, cause also the gods are mentioned as protectors of these sciences and arts.

With this connection between Muses and knowledge comes along a story given by Cicero [Cic. N.D. 3.88] where it was said that Pythagoras was sacrificing an ox to Muses every time he made a discovery on geometry; though Cicero didn't believe it.

So we have two main attributes of the Muses; music & knowledge, the latter via memory, teaching, logic. And if we look at the protected by them arts, they are all involved with music somehow; music, dance, theater, poetry, literature generally; thus possibly and every art that is related with words. Through epic poetry and teaching maybe history was involved. However, I wouldn't be sure about astronomy-astrology; as divine knowledge maybe, I can't know. Diodorus seems to connect the Muse Urania with imagination-thinking and following soul-lifting to skies-heavens; allegorical. It is Roman Cicero who is more clearly mentioning astronomical terms [Cic. Div. 1.17].

In any case painting and sculpture don't seem to fit so easily with these attributes; at least they wouldn't be the first of the arts that would come in my mind. Muses seem to represent something more spiritual and esoteric, rather than crafting-visual-arts. However, I can't feel 100% sure, cause maybe Muses could be considered their protectors more vaguely. While we should not forget that the majority of the visual arts' themes were taken from the Muses' arts; i.e. mythology and history.

However, painters & sculptors, craftsmen in general, don't seem to be without a divine protective presence, too. According to essays, the goddess Athena seems to have the lead, mentioned eg. around a weaver's work [Ath. 2.30] and a sculptor's [D.L. 4.6.45]. While another sculptor seemed to honor the deities Graces [=Χάριτες] with offerings for the completion of a work [Paus. 3.18.9]. There's also an allusion of some inspiration, not by Muses themselves, but through 'wisdom' [=σοφία] that should be related more with 'high knowledge'; this 'wisdom' is found in epigraphies around sculpture (3).

Finally, I am not aware exactly of the reasoning, however, it seems that it has also be noted a comparison between the visual arts in ancient Greece with the poetry, with some parallel course; by Webster already since 1939 (4) & (5). A comparison between 'Muses' with 'Athena', with possible common ground this 'wisdom'. However, the same author had written: "The belief in the direct inspiration of the Muses in its cruder forms belongs to the period before Pindar. The magical theory is the earliest of all." (6) Possibly an interesting approach, but without seeming to have a decisive impact on our approach, as presumably it's implying a parallelism not an identification.

To this Tanner writes: "But, whereas inspiration by the Muses gives poets access to the 'truth' (aletheia) and authorises their poetic voice, the gifts of Athena and Hephaistos are not so much a matter of inspiration as of manual skill and practical intelligence, metis" (2)

(1) Craftsmen in Greek and Roman society, by Burford, Alison, 1972, p. 207, in https://archive.org/details/craftsmeningreek0000burf/page/206/mode/2up

(2) Culture, social structure and the status of visual artists in classical Greece, by Jeremy Tanner, 1999, in Proceedings of the Cambridge Philological Society

No. 45 (1999), pp. 136-175, p. 141, in https://www.jstor.org/stable/44696751?seq=6

(3) check eg. IG I² 522 in https://epigraphy.packhum.org/text/1759 , and SEG 19:510 in https://epigraphy.packhum.org/text/215597 , both mentioned in Griechische Epigramme

by Geffcken, Johannes, 1916, nos 2 & 29, in https://archive.org/details/griechischeepigr00geffuoft/page/xii/mode/2up

(4) Greek Art and Literature, 530-400 B.C., by Thomas Bertram Lonsdale Webster, 1939, p. vi, in https://books.google.gr/books?redir_esc=y&id=b8BfAAAAMAAJ&focus=searchwithinvolume&q=%22taught+by+the+muses%22

(5) Greek Theories of Art and Literature down to 400 B. C., by T. B. L. Webster, p. 171, in The Classical Quarterly Vol. 33, No. 3/4 (Jul. - Oct., 1939), pp. 166-179, in https://www.jstor.org/stable/637279?seq=6

(6) Greek Theories of Art and Literature down to 400 B. C., by T. B. L. Webster, p. 166, in The Classical Quarterly Vol. 33, No. 3/4 (Jul. - Oct., 1939), pp. 166-179, in https://www.jstor.org/stable/637279?seq=1