A method of laser milling varied shape, geometrically repeatable holes is disclosed where a laser drilling system is provided to ablate material, desired hole geometry is determined based on customer specifications, ablation rate is determined using laser drilling system parameters, and a tool path algorithm is determined based on the geometry, ablation rate, and laser drilling system parameters. According to this production method, a methacrylic acid ester can be efficiently produced while largely reducing energy, resource and environmental load, compared with the conventional chemical production processes. In one embodiment, a method for forming a cylindrical target assembly includes filling a gap defined between sputtering target tubes with a spacer. Further, whether the position of the measurement site falls within the proper range is notified while correlated with the measurement result. A cover is moveable between a closed position that covers the waste opening, and an open position that opens the waste opening. Human operators are presently instructed to agitate such containers before installation into a marking engine but such agitation is unreliable.