This is a third slide conversion I did on a Schilke Piccolo Trumpet.  The owner wanted to be able to kick the slide out to adjust for intonation.  Everything was made in house.  The ring was cut from brass tubing, the base from rectangular bar stock, and the screw was turned from round rod.  For the stop that is soldered to the fourth valve slide, I turned a ring out of brass rod and bored it out to match the outer diameter of the tubing.  Then I cut out a quarter of it and shaped it a bit.  After cutting everything and brazing the ring and base together, I silver plated everything and soldered it all onto the instrument.  Then I lapped the slide so that it could be moved easily by one finger.