That part is a tool designed to help you thread your cabling through the twisted cable housing.
Can you confirm whether or not you have a fixed focus laser? I believe that module at one point came with a variable focus lens and later moved to a fixed focus lens. If you have a variable focus lens you need to be very diligent about getting proper focus. Fixed focus models make this a little easier. Those models come with an aluminum cylinder to help set ideal focal distance.
Any cutting operation in general is a non-trivial exercise and requires a good setup to do with success.
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