I recently did a demo at a quilt group and have been contacted for help so I hope that as a picture is worth a thousand words these four pictures....
well lets see....
If you were not there then I should explain that at Dunelm Mill fabric shop they sell zip by the meter and separate zips but they can be difficult to put together unless you know one very simple trick.
I have used black teeth strip and cream zip just for contrast.
Cut away the teeth for a short distance. That is it that is the trick.
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Thread teeth into zip on one side.
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Just tuck the teeth of the otherside into the zip.
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On a surface hold down both the fabric tabs and use your other hand to pull the zip. Ta Da
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Hopefully you are now smiling at how simple that is.