When I started jazz violin improvising, I got several Aebersold books. All of them have a page of arpeggios and scales in the key of C with the advice - "every musician should memorize and be able to play [these] in all keys." Jazz theory told me that 7th arpeggios contain the 3rd and 7th notes, and these are useful in many ways while improvising. I also found that 7th arpeggios in all keys over 2 or 3 octaves are difficult on the violin -- until I systematically found fingerings that are repeatable in many keys and easy to remember. That was the start of this book of fundamental technique exercises for improvising. From that foundation, I added exercises to develop swing rhythm skills, and a variety of exercises that combine notes (left hand) with rhythm (right hand). Jazz improvisation may look like it is "making it up", but it is the result of memorizing and mastering many skills. They're just different from Bach and Mozart skills. Enjoy where improvisation skills take you.