Unfortunately I don't have any plans nor do I have the cab since the owner wanted it to play over the holidays, in raw finish.
I simply made it 18inches wide to hold the 19in Dell 4:3 LCD.
The sides were drawn onto 48inx24in 3/4in MDF panels.
Then I used a typical 8.5x11 print of the profile to come up with the angles and kept working it until it felt right. PDF image attached.
I drew out all of the braces on the panel until it held the control panel and monitor properly, with the wood I had available.
The curves were simply done with a compass until I liked the feel.