Right. What are you evaluating for? You need to better define what it is you want to learn from the process. This will help you determine how to sample (frequency, number, and location.) How many lasers do you have? 1? 2? 20? Are you looking to determine laser to laser variation? If so, set up your sampling to gather pieces from each laser at some frequency. Is it time to time you want to understand? Over how long a duration do you expect to see a change? Sample within that duration until you see the change you are looking for. How many cappers do you have? Is it capper to capper variation you want to understand? Do you see variation over time on the cappers? How much? Set up a sampling plan to capture that variation, across cappers.
As you can probably tell from my questions, your best bet is to design the sampling strategy to answer the questions you have of the process. You must first determine what it is you want to learn, devise your strategy to learn that i.e. your sampling plan, then go execute your strategy (I recommend a trial run before you launch any large-scale study.)
Good luck!
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