also, what youposted is NOT a schematic, its called a layout, a schematic will be harder to read bot will better explain the flow of electrons so you clearly know which toggle position on the DPDT will be open or closed... if you can read it.... for reference here's a legit SCHEMATIC (though for something a lot more complicated, but I have it handy.... if you can read it, the power supply, signal flow and ground scheme should be clear as day):
http://www.lynx.bc.ca/~jc/yvm-1.jpg
if you are the least bit confused about what to buy and how to wire it JUST BUY the boss box or the loopmaster NC box with 2 switches, don't be a tool who solders every terminal trying to figure it all out
if you don't yet have it pictured in your head and know who makes the most durable parts for the most stressfull applicatons of this simple logic circuit then quit and buy what you need... in the long run it'll be cheaper than fucking it all up and trying to correct things
if you don't GET IT don't fuck around.. with a modicum of respect, you are a young guy with the attention span of a gnat and a very questionable attention to detail... the reason to build stuff is NOT to save money, though it CAN be cheaper, if that's your only goal surf flEaBeay and ignore my suggestion you build the 2 button switch...
if your goals are mainly educational then proceed