^^ More on the spark chamber in my long list of headcanon illustrations... bleh, I must!
A part I've named the fibrobole, a softer, fibrous section of the spark chamber, plays a key role in Cybertronian reproduction as it's the only reliable way to access Innermost Energon to contribute to a viable protoform (most use an instrument, but those with sharp-tipped digits can use their own digits... ouch! 8O). This fibrobole can be punctured and seal itself back up almost instantaneously. Ouchies--but all part of the natural process of turning a protoform into a robo-beb. :3c
Colored pencil and colored ink!