The power supply I designed and built delivers steady, regulated 12 volts, 9 volts and 5 volts all at the same time. Each voltage has two outlets, but they can be "daisy chained" with a custom cable to connect many more pedals.
The styling is an homage to the old days of vacuum tubes, when components generated so much heat they needed to be on the outside of the casing instead of inside. I used some gigantic capacitors that I thought would look cool, other than that they are major overkill.
In this Instructable I am going to assume that you know some basic electronic skills and know what I am talking about when I say capacitor, resistor, LED, transformer, AC and DC, etc. There are lots of introductory electronics Instructables and soldering Instructables you can check out if you'd like to gain a better understanding of basic electronic principles and components.
IMPORTANT NOTE: Depending on what pedals you intend to use this for, you should take care to wire the DC connectors as pin-positive/ring-negative or pin-negative/ring-positive. The latter is the industry standard way of doing it, although it poses issues when building a pedal that has a metallic housing. I prefer pin-positive/ring-negative because of that issue, and I wired this supply in this way. Please take care as to which way you wire the power supply to prevent damage to your pedals.
Step 1: Planning and Schematic
The schematic I designed can be modified for whatever voltages you would like. For example, if you don't have any 5V pedals, you can just swap the 5V power regulator for a 9V regulator, and now you'll have double the 9V power.
The schematic uses a simple power supply circuit converting AC to pulsating DC, smoothing it with capacitors and running it through voltage regulators for fixed DC outputs.
Here is a higher resolution version of the schematic if you can't read the one below very easily: