Designing Your Float
Before you can build your float, you'll need to have a design in mind to work with. Usually a parade has a theme to it, so your design will probably tie in with the theme. Christmas floats are both popular and easy. The people on your float can dress in costumes, and simple scenery can be added in the form of Christmas trees or a cardboard cutout of Santa's sleigh. Check with the parade founders about regulations and restrictions for the floats. You'll also want to budget how much money you'll spend decorating the float and how much the entry fee is to ride in the parade.
Building Your Float
To create a moving float you'll need a trailer and a car or truck to pull it. The type of trailer you have will determine how to build your float. For a hay trailer--a trailer with no sides on it--build a skirt frame out of 2-by-2 pieces of wood. These are simple frames stapled or nailed to the sides of the float to hide the wheels from view. All that you'll need after that is to decorate the trailer with your float. Nail down or staple anything that might fall off. It will be much easier to create a float on a trailer with sides on it. Either decorate it as it is, or create a skirt frame and attach it to the sides. The frame will already be there; all you need is to create the interlocking pieces of wood to which the material is attached.
Moving Your Parade Float
Once your float is finished, take it out for a test drive. Attach the trailer to your vehicle's trailer hitch and make sure it's fastened down. Drive it around and see if everything holds together. When parade time comes, double-check that everything is securely fastened and add any finishing touches to your float. You'll also want to make sure you have a full tank of gas before you hook up the float. Make sure the driver goes slowly and has driven the route beforehand to anticipate any sharp turns or hills. Normally, parade routes are flat and easy to drive at slow speeds.