You can scan the manufactured objects with a camera connected to computer USB. Then compare the scans got with a reference standard. Apply a tolerance for acceptance or rejection. Based on the quantity of rejections improve process, till faults are within acceptable limits.

The scanned object must be in same position and same angle for proper results. This depend on some guiding system in conveyor to make object position properly.

some links to further your study.

evaluationengineering.com--applying_automated.asp
digital.ni.com-Optical Inspection
process-equipment.globalspec.com--inspection_machine
perceptics.com--machvisionoverview.html
thomasnet.com--inspection-systems-food-packaging
devicelink.com--/07/02/007.html

delabs