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What browser are you using? You can't access them, there is no link but you should be able to see them.

You could file the business end of the nail to a triangle shape. I believe a triangle can be used to sew waterproof (or water resistant) seams in leather. Am I correct on that YCC?

Here are a bunch of plans for home made tools. These are larger power tools in most cases.

http://www.green-trust.org/junkyardprojects/FreeHomeWorkshopPlans.html

That would probably be a good strong leather or pack gear needle. Nice job!!