I think "snap spool" might be a German-specific translation. I've never heard of a snap spool in this context (or any other, for that matter). I've heard of "snap-on spools," but I'm not sure if that's the same as what you're looking for. I think most welding or soldering wire simply comes on spools, no snapping.

If it is fully enclosed, as I picture it, then it can be called a 'dispenser reel'.

Thank you. As I have no picture of the "Musterklappspule", it's difficult to tell. What about the first part of the noun "Muster-"? Is it okay to write "sample dispenser reel" or isn't it necessary to mention it?