I bought an old wash tub a few years back with great intentions to do something amazing with it. I moved it around the studio a lot and it finally wound up in my back room. A good customer of mine came in for a visit and was saying what a hard time she was having trying to find an ottoman. A light went on and I showed her the wash tub and said I could "try" turning it into an ottoman for her. She immediately went to the fabric store and bought the fabric and came back.
I was stepping way out of my comfort zone on this one as I am not a wood worker or carpenter. I also have very limited tools to make items. To start I needed to know the height requirement. You don't want your feet too high or too low when you are sitting so she called home to get the measurement of the height from the floor to the top of the seat of the chair the ottoman would be used with. The wheels added some height and the foam would be thick to add the remaining height needed. A local fabric store cut two pieces of foam to the square size and glued them together to get the correct thickness.
The top piece will consist of two pieces of wood, one cut to the same size as the outer edge of the wash tub and the other board cut to the inner edge of the wash tub. Both boards were glued together to act as a snug lid that could be removed. The foam was placed on top then and trimmed with a steak knife to the correct shape, a thin layer of batting then the fabric over it all. Using a staple gun I secured the fabric to the bottom side of the top board and then trimmed off any excess fabric. I finished the top with black decorative nails along the edge of the fabric on the upper board.
There was some rusting and very small holes in the bottom of the tub so I sprayed the interior with black rubber for rocker panels.
The wheels were attached with small bolts through holes I drilled in the bottom of the tub. I used two regular wheels and two with brakes. You don't want your ottoman rolling away on you.