Pinky trills are interesting.
You try to avoid them on keyboards.
They are unavoidable on wind instruments.
Unfortunately for violinists, the right hand pinky trills are more common than the lefthand ones (G# only, on flute and oboe, but clarinets may have more).
So a piece of Corelli/Geminiani I'm playing has a pinky trill which doesn't worry me, but I do wonder if you have a favourite étude for pinky trills on the violin?
4th finger trills can usually be avoided by shifting to another position, even if it is only for that one note. Don't have the 1st and 2nd fingers down while doing a 4th finger trill (or vibrato). Some players are blessed with a longer 4th finger or have anatomically completely independent 3rd and 4th fingers. For early music, like your Corelli piece, don't try to trill too fast. Think of what a singer would do with that trill. And then there is the double stop trill - that's advanced class, beyond me. Kreutzer #s 16,18,19,21 have plenty of 4th finger trills, just be careful, don't hurt yourself. For all fast stuff I found it helpful to mentally focus on lifting the fingers quickly.
Dont, Op. 25, No. 6
Joel gives good advice. An additional place to work on the light finger-lifting is on the first page of Schradieck. (I think it's) the second line with the 2-3-2-3-2-3 followed by the 3-4-3-4-3-4 can be practiced pretty slowly, but with each finger lifting as quickly and as silently as possible.
What's a right handed pinky trill?
I’ve found that my 4th finger trills are better/easier after having done Kreutzer 9. It’s not specifically for trills, but it does work wonders for finger independence which is why I’m studying it.
i play the recorder too. for my luck there are almost zero repertoire who uses right hand pinky trills (because it's the lowest note and not everyone likes to compose with it, i don't know why
Mazas 13 and 14. Also general fourth finger exercises such as Mazas 19 or those you find in Schradieck type exercises.
continued,-- Another vote for Kreutzer #9. For an easy exercise prior to those heavy etudes:-- Somewhere in Doflein book 4 there is an exercise I call "taps and lifts" I still do it as a warm-up. It develops finger independence, velocity, and gives you a good trill as a bonus. Another factor not mentioned yet is how high you lift the fingers. 1/2 inch, or 1 cm, or the height of a fingernail is about right. Too high-the fingers travel farther, and land too hard, producing popping sounds on the fingerboard by some players. Too shallow a lift; the finger doesn't go all the way down to the wood, sounds mushy, and surprisingly slow. And then there is the vibrato trill used in East Europe folk fiddle-- but it would be malpractice of me to even suggest it.
Fiorillo #2 makes regular 4th finger trills feel easy after the prolonged 1-2 and 3-4 double stop third trills you have to do. I wouldn't say this etude isolates 4th finger trills in particular though.
Paganini Caprice No. 3. They must be pinky trills if you do trills in fingered octaves ;-)
Lists of studies are fine, but they don't tell us