When I was getting married (unknown to me at the time) my fiancee called the customer service number for LEGO (the one based, at the time, in Enfield, Conn, USA), explained that she was marrying a major AFOL and asked if they made a cake topper (this was before there was anything official along those lines). The girl on the line said she wasn't aware of anything but would "look into things" and took her contact information.
A couple weeks later, a plain padded envelope arrived in the mail with two minifigures (with three different hair colors for the bride) flower parts and parts to build an arch along with a photo of what the assemble "kit" should look like and a note from LEGO congratulating us on our upcoming wedding.
One more reason why LEGO is a great company.
Anyway, the arch design they they sent us was made from two curved fence parts
and four straight fence parts
held together with some 1xX plates plates on the bottom/backside and 1xX tiles on the top/front. The whole thing was then flipped on end to get the arch shape and held to a plate with some 1x1 clips
. I think it's nicer than the commercial one they eventually produced but your milage may vary.
In any case, congratulations!