The classic Pumpkin has eyes and teeth cut right through to the inside. But by carving shallow cuts into the flesh, more complicated patterns can be made. I did this with my little pocket Swiss army knife. I had to cut each swirl twice, a cut on each side of the line. Next year, I might see if I can get a better carving tool. and be a bit more adventurous.
The kind of pumpkin is important. Some have very thick skins and tough flesh inside. This one was nice – it had quite a soft skin and nice dark colour to contrast the light inside.