Old School here to promote a great post from Eldar Addict. He used a kids craft kit called Shrinky Dinks to make Bone Swords for a Swarm Lord - but the great idea here is that you can design something at 3X size (like chapter symbols, chaos icons, hard to carve parts) and then shrink it in the oven. This means that folks who are just starting with plastic card or folks who have trouble carving small details in card can now create their work in a larger format and then shrink it down. I have never seen this before in all my blog and forum whoring, which means that this is one hell of a great discovery by Eldar addict and I am very happy that I have been following his blog these many months.
Don't take my word for it, look at these photos and then go check out his guide here.
Starting with a 3x sketch, he begins to design his bone sword.