Custom make one from aquarium, then you can get exactly dimensions to meet your needs. I am no handyman and I made one to fit my skimmer, refugium and return in an afternoon. $75 would be more than enough to acomplish this. Do searches and you'll see all kinds of ideas. FYI I used ge silicone one with no problems there was some controversy over this. $6 for a 10oz tube or I would've spent $30 on silicone. Start posting for used aquariums these guys all have them laying around.