I have a friend that is an effects junky... and to save himself money... he builds his own. I have a good knowledge of electronics and a good understand of tone... in electronics terms. So I wouldn't feel out of place or in-over-my-head if I tried to make one up... However, someone who doesn't have the knowledge of basic circtuitry may find it very difficult to follow the schematics. Do some research and gauge how knowledgable you are no electronics... if you think you can... you can.

"I dream... therefore I can"
I don't remember who said that... but it's a good quote.

Good Luck