I guess the question is always around to build or buy. In this case, I picked up a 18 site Clone Bucket at the local hydro store for $80. I figured the time to run around getting parts and cutting 18 2" holes in the top of something was worth the buy..

As far as keeping the water at the optimal temperature, I just set the bucket on my seedling heat mat and attached the temp sensor to the side with the suction cup.

Peace, Farmer Rich