I made one out of some scraps, but didn't have any plans. There wasn't much to it and I think I got some rough measurements for it from one I found on line. I cut the holes to match the lip on the bowls we found at one of the pet stores. If there's anything I can help you with, let me know.
Here is one I helped my 13yo son build for his Great Dane. No plans it was just built from a picture using pocket screws. Now we have two Danes so I just built another that has 3 bowls. Two for food the other in the center for water. I donít have a picture of it right now but I would be glad to take one and post it for you when I get home.