The external one seems OK . I took out the 2nd drain to replace a gasket. I have since removed the two inner partitions where the utubes would have resided so the rear box is now open between the two rear box drains. As far as making new boxes via diy, I think I would buy the kit from synergy reef instead. If I reused the two halves of the hob I have, seems like the only thing I would need are two bulkheads and two holesaws. One holesaw for the acrylics and one for the glass. Can anyone tell me whether this plan will work or not?