'technic'-ally speaking

My son has an upcoming birthday, so in preparation I asked him what he'd like his cake to look like.  He was thoughtful for a moment and then said, "It can just say happy birthday."  I asked if that really was all he wanted, he was thoughtful again and then said, "Well, I would really like a model of a Lego Technic Motorized Excavator on the cake."  Then it was my turn to be thoughtful (I was thinking, I've got to stop letting the kids watch so much Food Network).  We came up with this idea as a compromise, I made a 2D sugar image of the motorized excavator to place on the cake. 

I taped an image of the machine along with a piece of waxed paper to the counter.

Then I simply traced the image with royal icing (meringue powder, confectioner's sugar and water).

I'm allowing the icing to harden for a day, fingers crossed it will stay in one piece while I place it on the cake!

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update: It worked.  The cake I put the excavator onto wasn't that pretty...but my 8 yr old was happy.