Made a scale to weigh the dog. Uses load cells and an Arduino Nano to read the cells and show the values on the LCD display. It is self-taring so that all one has to do is turn it on, wait 3 seconds for it to zero, then (the hard part), convince your dog to sit on it. (Photo shows an Arduino UNO but I used a Nano because of smaller footprint.)
I used plastic that I had kicking around but you can use 1/4" plywood if you want. I support the wood on the 4 load cells using 1/4" aluminum strips.
I replaced the plastic because it was too slippery and worrisome for the dog, putting a piece of rug on top of the plywood. I calibrated the scale using some calibrated weights.
Hover over photo for description, click for larger.