This is one of he best ideas I have seen in a while. Simple and cheap to build. Copper has come down a lot in the last few months. Once could build this for under $10 and a lot less if you have some of the stuff already on hand like I do.
I'm gonna take this to the next level and see if I can make it look like a traditional mash paddle. Shouldn't be too difficult. Might have to bend some pipe to get the angles right. I'll post back with a pic when I get it finished. I have a wooden one, but this is just such an appealing project I can't resist. I think you have a winner with this. Just thought of something. You could drive a dowel through the tee at the top to make a wooden handle. Is this made from 1/2" pipe or 3/4"? It looks like 1/2" from here. Do you think it is strong enough? A couple of more verticle tines on the paddle part would probably make it work better. These could be horizontal cross bars instead of vertical. I would leave the pipes round. The round dowel type rakes move very easily through the mash. It's one of the most effective tools I have in my aresenal. Makes the dough in and stirring a breeze, expecially when compared to a long handled spoon.