I'm planning to build a DIY A/B/Y box. I was wondering if any of you guys already made one and how simple/complex it was? Did you get any hum? Is it worth building it?

I found this:

I'm a total newbie at electronics, I just want something to build and have some fun. Is the second model in the link better in anyway? Do they mean with enhanced that it has LEDS?

Also I found jacks with 'normalling contacts' and without them, does it matter which I take?
Also can I ditch the battery connector and use only a DC-jack?
And what resistors do I need to put in front of the LEDS?

Thanks in advance
Looks fairly simple from the link you found. The second one just has the addition of LEDs incase you need them to know which is currently selected.
"Air created the greenness. And once you've got something, that leads to otherness." - Karl Pilkington.