One is about 8x8x4. The other I thought I would experiment with longer and fewer runs of metal. It is closer to 15x7x4. The metal strips are all 2 inches and the MDF is 1/2", hence the 4 inch box depth. I was trying to have a greater amount of copper versus aluminum but not by much in the end.
I was not sure on running through the box as dead-heading is safer and avoids any ground loops. But I put it in out of curiosity and perhaps running to ground might add some performance. But if it does, why not just use a filter network instead of box full of dirt and minerals?