Who is telling you you can't use a scissors? Make your own templates and use your scissors. When I started my mom made templates out of cardboard and put sandpaper on one side so it wouldn't slip for me while I marked around it. Use what works for you. If you want a quilt out of squares go for it - size doesn't matter. If you want to make a Postage stamp quilt but your squares are bigger than 2 inches you could always call it an Inflated Postage stamp quilt.
If you want to quilt remember there are no set in stone rules, only suggestions.