So far as I know, these have never worked on anything except stringed/necked stringed types. Anything else gets the "this combination won't work" message. Which is different than if the item is scripted, or already has a strap. I'm not saying they should all be allowed to have straps attached, since it really doesn't make sense for a lot, or even most, of the instruments (a flute/piccolo with a strap?). But they definitely won't all work.
Normal, non-scripted:
As you hold your wool-lined strap up to the thanot tambourine, it becomes clear that the combination won't work.
As you hold your wool-lined strap up to the black plaid bagpipes, it becomes clear that the combination won't work.
As you hold your wool-lined strap up to the smooth ivory flute, it becomes clear that the combination won't work.
As you hold your wool-lined strap up to the pale glowbark crumhorn, it becomes clear that the combination won't work.
Already has strap attached:
You notice that a carved rosewood harp is already equipped with a strap that allows you to wear it.
Scripted, not allowed:
You consider attaching a leather wool-lined strap to your rosewood mandolin, but something about the mandolin makes you stop to reconsider.
Allowed:
You hold your wool-lined strap at either end of the oak harp, assessing how the strap would bear the weight of the harp if you were to wear it over your shoulder.
[Repeat this command to permanently attach the strap to your harp.]
