the .45ACP (Automatic Pistol Cartridge) make a MOST EXCELLENT "Plug" style Cigar Cutter. The size is perfect for a wide range of cigars.
There is a little trick that I use though, which greatly improves upon the original Plug style cutter. It is very simple but I have yet to see a manufacture actually use it!
I made this at TechShop Menlo Park
Read on, if you are a cigar smoker that happens to have access to spent cartidges :-)
Step 1: Find a .45 ACP cartridge (spent...), check it for roundness and condition
Find one that is nice and round; My sample is here is from a very high quality round; it is a nickel plated brass cartridge.
Step 2: Remove the Cap
Stand off the cartridge from a hard flat surface by using a washer or machine nut which has a hole LARGER in diameter than the cap.
Find a very slim tool; a punch, a jewelers screwdriver, allen wrench, etc... Place it down the open end of the cartridge and into the little hole in the bottom.
Now, using a small hammer (or other suitable stand-in for one) tap the punch gently...the cap should pop right out.