I used plywood (sand well to avoid splinters) and 2x4's, some paint colors I love, stain.
I had to think a bit about the construction of this, mechanically minded I am not. I am so sorry I do not stop and grab my camera when I am in the process--I just get in the zone. I will try to explain it: I screwed down through the top of each square plywood into the 2x4's, making sure to countersink the screws. I then stacked them and drilled through the 2x4 at an angle on the inside--if you look closely you can see the screws. There is a probably a better way to do this, but this is what worked for me.
I added some wheels, some feet would work too, but I liked the industrial look the wheels gave it.
Find more ideas at Miss Mustard Seed's , My Repurposed Life
Finding Fabulous at Funky Junk Interiors and at French Country Cottage and at