Yea I built mine 16" x 16" as well as you can cut clean 8ft 2x4's into this length and have no small scraps. I made mine 8 stacked high so they're right at the top of my jack which is nice. Feel 100% confident crawling under the car, which I never was on jack stands.
Wish I had built them sooner. Cost about $35-40 in materials.
