I invoke the deep magicks of nerfhaven. Is there a reason we never used doorknob latches as catch mechanisms? They're already shaped perfectly for a plunger to slide over them, and they come with a built-in trigger mech. Did they just not have strong enough springs, or was there another reason I never saw these in the pre-3D printer days?
Huh. This might just be one of those obvious-in-retrospect ideas that nobody thought of.
I don't think they'd make a great catch, for whatever it's worth. Bulk and weight is an issue; connecting them to an ergonomic trigger may be another. Handcarving something usable that's much smaller out of plastic hasn't proven to be too difficult.
With that being said this could make a wonderfully giggle-worthy build.