A spring motor mechanism for use in an injection control device having a metered/controlled injection rate proportional to the rate of withdrawal/injection suitable for cosmetic as well as other applications is described. After the cannula is advanced into an object (person) the cannula is withdrawn to create a tract or tunnel within the targeted area. As the cannula is withdrawn, filler material in the injection control device is uniformly deposited into the tract or tunnel via the automatic metering system. As one feature, the spring motor mechanism automatically retracts the positioning guide that is used in the metering systtem. The spring motor mechanism may be replaceable or customizable, offering the user enhanced safety and convenience of operation for the injection control device.