Press space to initiate program, then enter color, shade, line length change, starting line length, degrees and pen size. After that, the program will start and never stop until you hit the stop button. Press the green flag to reset everything. Enter misc. numbers for color and shade. You might want to look up the scratch color palette numbers so you can choose a color you want accurately.
FYI: It's not really a Spirograph creator... I just named the project that because it looked like it. I was bored in tech class so I started this and then built off of this. Feel free to remix this into your own versions. In the future, I will add a feature that will enable you to have changing RGB values as the Scratch cat creates the Spirograph. I will also probably create a program that allows you to create a circle Spirograph. UPDATE 3/30/2017: There is now a program for that! Search "spirograph creator" and if one besides this by me comes up, please check it out!