Some people like me were dissapointed to find that Perceptors Titan Master head was to be kept in the microscope tray, this is a little add on to keep Convex tucked out of the way while Perceptor examines something that isn't his own heads navel. Handily also doubles as a filler for the underbelly of his tank mode and weapon storage for robot mode.
Because this pegs into a 5mm socket, I have made the peg a tiny bit bigger than the socket to keep it tight, you may want to sand it down a tiny bit if it doesn't fit your fig, if too big let me know so I can change it.
Pictures show home printed & tested version, actual product will differ.