Just a thought. If you still have your first empty spool and if it is the same as the second spool, weigh the second full spool and subtract the weight of the empty spool to figure out the weight of the zing-it and then find out the weight of say 10' and then divide that into the weight of the spool. Disregard if you don't have a scale.
This... is hilarious! Yes, it would work, but it's still hilarious.
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