We are sorry to let you know that we do not make covers for the pens.  Since we have not conducted any safety testing for a cover, we are not able to give advice regarding the idea.  However, it is important to keep in mind that the open top allows for air flow and covering the top could impact the ventilation.  In addition, the pen has a very minimalistic design so it is difficult to find a way to secure a top.  Therefore, we recommend using the product as is without a top.  Our pens come in 27" height and 36" height. If the 36" height is not tall enough to contain your pet, then unfortunately we would recommend trying a different product.