It's a little thin, and needs some reinforcements. Also needs to be enlarged a small amount so it can fit better. Here is the first print of the lid.
http://blog.ponoko.com/2012/08/28/3d-printed-canning-jar-accessories/
http://www.thingiverse.com/thing:27385
http://www.treehugger.com/green-home/four-open-source-3d-printable-mason-jar-lids.html
http://www.3ders.org/articles/20120825-8-functional-3d-printable-mason-jar-lids.html
http://lifehacker.com/5937840/make-canning-jar-lids-and-accessories-with-a-3d-printer
More after the jump.
