Okay, so it's time-consuming, frustrating and challenging. The advantage is, in a given design you can swap a resistor for a potentiometer, and get a variety of sounds that an off the shelf effects pedal won't have. Or, where you see a capacitor you might be able to add a multi-position switch connected to capacitors of various values for a multitude of unique sounds. Once you control the design, the possibilities are endless.
My only successful project so far is a mosfet booster that works great. When I first built it, the only container I had around the house was a specimen test vial from the hospital, but then I put it in a standard black box.
Some great projects are here, including my booster:
AMZ
Other designs can be found at:
Geofex
Harmony Central
General Guitar Gadgets
Vintage Guitar Effects
There's enough here to keep you busy until the wee hours.
Also for your edification, some of my favorite stuff:
Z.VEX
Blackstone Appliances
Fulltone
Voodoo Labs
Hughes & Kettner
Some of these sites have sound files of their effects...fun!
