The Pumpkinhead is almost entirely black in color. It has a simple handle, a facsimile of Jack Skellington's head adorning the hilt, and a jagged guard with thin, white veins that is modeled after Jack's bowtie. The shaft of the blade is thin and long, and the teeth resemble a stylized bat hanging from the blade. The Keychain token is a jack o' lantern.
The name "Pumpkinhead" references Jack's position in Halloween Town, the "Pumpkin King". Both Jack's head and a jack o' lantern are part of the Keyblade's design. [Source: khwiki]
You can download this papercraft model template here: Kingdom Hearts - Pumpkinhead Keyblade Free Papercraft Download