Haven't seen a mold or cutter, but I just put this photo into my favorites. It actually looks like she cut straight posts, used something curved (maybe a decorating tip) to cut out the post and then cut the tip into a point. This is probably not what you are looking for, but I thought it was clever.
www.cakecentral.com/cake-photo_331863.html
Yes, it would be simple to cut thin strips of fondant. If wanted you could run a strip or two the other way to keep them attached together. Best to do this as you work - placing the fondant right onto the cake as it is cut.
http://www.cakecentral.com/cake-photo_65777.html
here is a template
and a couple cute pictures for inspiraion
http://www.cakecentral.com/cake-photo_1217857.html (this is a very cute fence idea)
http://www.cakecentral.com/cake-photo_1166021.html
http://www.cakecentral.com/cake-photo_1214788.html
good luck
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