Vassos often inserted case projects as separate pieces in his pre-drawing, suggesting that they were designed with the same care and attention that the instruments themselves received. And with the three harmonica models manufactured, their cases also have foray lines, matching colors and metallic surfaces that have improved the look and aesthetics of the instruments they held. This question of temperament led the Mellotron to be considered a difficult instrument. There could certainly be mechanical problems that would contribute to that. For example, the original Varispeed servodesign was bad, but improved considerably thereafter. The tapes stick to their frame and refuse to rewind if the frame is distorted by the carefree use of the machine. Smoke, temperature and humidity also played an important role. Such problems led to Robert Fripp`s widely used quote: “Tuning a Mellotron doesn`t.” Well maintained, but the machines behave much better than their reputation suggests. Harry Chamberlin spent a lot of time (mostly from sunrise to sunset) experimenting with sound and transformed a passable wardrobe like his first home studio. After receiving the right acoustics in the room and changing the acoustics of other rooms in his house, Chamberlin`s first recordings were made. All of Chamberlin`s recordings were recorded and performed in the late 1940s and 1950s by members of the Lawrence Welk Orchestra.
Welk was impressed by the idea of a tape-reading instrument and offered to finance its manufacture if it was called a “Welk” machine. Chamberlin turned down Welk`s offer. The correspondence of archives and patents show that Vassos believed that his elegant harmonica designs were improved on the historically rectangular model, such as that of Hohner`s famous Marine Band, whose design has hardly changed over time. Vassos` use of curved angles with light and fashionable colour combinations makes these playable instruments look like works of art.