I'm one of these persons who doesn't like to go and pay because very often there is an easy way to do it / solve the problem. Eveyone has some cardboard at home, I have loads. Ok, piece of cardboard and then like the pictures show, I made "trousers", piece of cardboard, measuring one leg 3 cm then ½cm gap and another 3cm wide leg. That is the tool. Notice that the longer the legs are, the easier it is to tie a bow.
Width of the leg is the width of the "loop". Because this is not costing anything, you can cut as many and as wide "trousers" you like. Hahaa... This is clever, easy, fun and cheap.
If I don't glue it immediately onto the card, I put a clip to flat it out. If I make a card I will put some glue also in the bow and then I use the clip anyway :D It will stick onto the card and also the tie won't open or spread.
This guide *so to speak was done with no proper preparations, but I will make another one. I might. Not sure. I could thou...
VIDEO AS WELL :D Oh yeah. Of course you spotted my new Fiskars scissors <3
Edit 15th February 2011
Great!!! I started making bows this way, too, but I usually use a fork :-) you can also make tiny bows then...