There is a company that sells a "stick on" fretted fingerboard for violins to help beginners culivate correct finger positioning.[quote]
firstly the fiddler has to learn how to tune,the best way to do this is to LISTEN to a note/sound,fidlers are much better off without strips but just listening,preferably playing along with a fixed note instrument,or with another fiddler who plays in tune
stick ons do not develop the ear,much better to blindfold the fiddler,and get him to play slowly,with a fixed note instrument. preferably long notes guessing whether he is sharp or flat, adjusting and developing his her ear.ITS ABOUT LISTENING.