To add on to LukeDancy's answer. The same paperclip offered by Penguin IS available at any store that sells paperclips. It's quick and easy to buy them from Penguin, but you are not limited to that.
Answered at 10:41pm on March 7th, 2014 by Nilpo (6 karma)
The ones recommended can be found right here http://www.penguinmagic.com/p/4030
It's not that you can't use others it's just that if you want to get the maximum results you should use the ones supplied and mentioned above.
Answered at 02:16pm on February 23rd, 2014 by LukeDancy (23 karma)