Measure your mattress. Using the measuring tape, measure the width and length of your mattress. You will need these measurements to ensure that the frame is larger than the mattress.
Measure your milk crates. Measure each of your milk crates and record these numbers as well. With the milk crate measurements and mattress measurements in hand, you are ready to assemble.
Lay out the pattern. After you have gathered both sets of measurements, lay out enough milk crates to measure slightly larger than the mattress set. If you are trying for a platform effect, lay out enough crates to measure slightly smaller than the mattress. Put the crates open-end down.
Strap the milk crates together. After you have laid out all of the milk crates, zip tie all of the crates together. Attaching all sides with the zip ties will give strength to the construction. This completes the milk crate bed frame. Place the mattress on top of the crates.