this is what i have for mine. the front is wide open i am thinking of putting some vents in on each side even though i have not had any problems with the heat. i used this all last year without any problems.
Built my own out of treated wood and trex decking boards for the top. The top is lined with truck bed liner on the inside to keep everything dry. The box sits on pavers on all four corners to keep it from soaking up water and the pump/filter also sit on pavers with level sand under them to keep everything uniform and dry. The side boards all have a 1/4 inch gap to let air circulate.