bonita - if you are going to add a sump - ADD A SUMP! I don't think you would be happy with a 5 or 10 g model down the line as either one only will run 1/2 to 2/3 full. A 29 g tank is the smallest tank size I have come up with to make a viable sump system out of. By the time all equipment is moved out of the display tank and placed into the sump things will get cramped even in a 29. Section off 8 inches for first filtering chamber, blue filter pad dripping down onto more LR. Double wall as we discussed on your other build. 8 inches on other end for return pump, with a double wall prior to it. That leaves only about 8 inches in the middle to put a skimmer, heater(s), filter, etc. It's tight but it can work well. As for how to do it, find a small enclosed nightstand or endtable you like, beef up the bottom, set it next to tank, and drill holes in the back of it to place plumbing lines through. The top makes a nice plant stand next to tank. In the meantime plan ona new stand and what the heck a BIGGER system!
Dennis