I built this box for a friend about 30 years ago. He went with a smaller powered sub and didn't want it anymore. I thought it would be cheaper and easier to rebuild this one than to build one from scratch. It is made of 1 inch mdf and is fairly well braced and used to have 2 15s in a push-pull set up with 2 4" diameter ports. Outside dimensions are: 33" x 24.75" x 16.25". It would be easy to turn it into a sealed box or to change the ports. I will be using an external amp(s) and electronic x-over to power it and was thinking of using an 18" in it. I will be using it in a stereo rig mostly for music. I have a budget of $300 - $600. I haven't built any speakers in years and would like to get some ideas on which way to go to make this a quick easy project. THANKS!