This is a cover I made to go over an old pool slide base. It was specifically designed to fit over my particular dimensions, so it may not work for other scenarios without modification. This was designed to print from the bottom up without supports. There is a center section built into the model that has a .2 mm gap between the part and the bottom. This can pop right off after you print if you desire (it was added to remove the need for supports).
Each instance of this will require the part to be printed twice, once for each side. It is held together with two 1 1/2 inch (38mm) bolts held together with two half inch (13mm) nuts. For my print I used square nuts so they would lock into place with the square cutout. However, it should work fine with standard nuts.