It’s two feet by four feet. And four feet tall. Total footprint is a 2 inches bigger due to the mounting plates for the wheels. All 2x2 .120 wall tubing. The posts on the outside were to keep the material from falling over, and it works well. But if you don’t have it loaded equally, and a bunch of steel flops over, it may be able to tip. I haven’t had that happen, but I can see how it might.
I used the tubing on the outside to hold other small scrap by welding some mesh to it.
The floor of it is just square tubing running the short distance of the frame. I didn’t want to use mesh either for fear of it catching. It seems to work just fine how I have it. If an edge gets caught while sliding in, it’s not hard to nudge it over the tubing.