Arpeggios are an incredibly common figure in violin music. Most of the limitations you seem worried about simply don't exist. Arpeggios are just notes to us; there are no special rules about which strings or fingerings are expected.

If you want to be extra nice to the players and make everything easy (or if you have very fast arpeggios that need to be easy):

• Avoid perfect fifths that aren't on open strings. The same finger has to jump, which makes it hard to play smoothly and in tune.

• Avoid jumping over strings (e.g. from the G string to the A string). Self-explanatory.

• Keep your repeated figures within a range of about two octaves or less, which is what the hand can reach without shifting along the neck.

• Don't pick a key with more than like, four sharps or flats. No one wants that.

None of these are rules; in fact a whole piece that observed all of them would be a dream. But they should give you a basic concept of what is and isn't easy.

As for cellos, I don't play one. I know that if you wanted to translate the ideas above, you'd replace "fifths" with "fourths," as that's how cellos are tuned, and "two octaves" with something closer to an octave and a half. If there are further intricacies, I can't tell you.

As Peter said, when in doubt, ask someone who plays the instrument to test what you've written.

Arpeggios are an incredibly common figure in violin music. Most of the limitations you seem worried about simply don't exist. Arpeggios are just notes to us; there are no special rules about which strings or fingerings are expected.

If you want to be extra nice to the players and make everything easy (or if you have very fast arpeggios that need to be easy):

• Avoid perfect fifths that aren't on open strings. The same finger has to jump, which makes it hard to play smoothly and in tune.

• Avoid jumping over strings (e.g. from the G string to the A string). Self-explanatory.

• Keep your repeated figures within a range of about two octaves or less, which is what the hand can reach without shifting along the neck.

• Don't pick a key with more than like, four sharps or flats. No one wants that.

None of these are rules; in fact a whole piece that observed all of them would be a dream. But they should give you a basic concept of what is and isn't easy.

As for cellos, I don't play one. Most of the above would still apply, but if there are further intricacies, I can't tell you.

As Peter said, when in doubt, ask someone who plays the instrument to test what you've written.