I love my cart by Armstrong Medical A-Smart Crat system. The catalog is full of different carts styles and all kind of accessories. I have on my cart extra bins an IV pole and extra folding tray. It is metal on 4 wheels but unlike the note by David Longseth I have no problems with it, I do not push it around but rather pull it behind me. It is a great cart that holds everything, I can do 5-6 PICC without reloading the cart.
"One word...plastics."
The metal cart I have to lug around weighs 72lbs,empty,and has 4 wheels that like to go in 4 different directions.
Plastics!