This is the basic design that I used, it was easy to build and its tried and true. Most of the 125vgallon and below stands that people build on this site are basically variations of this.
View attachment 985684
(source:
http://www.reefcentral.com/forums/showthread.php?threadid=1169964)
For a 75 gallon, use 2X6's on the top (red and yellow pieces), and keep 2X4's for the side pieces (purple, green).
Cover it with 1/8" plywood of your choice, and then put wood trim around it and stain. Make whatever style cabinets you'd like, and although its a pain in the butt, I highly recommend making a solid bottom to the stand so nothing "falls through the cracks" on the sides.
For my tank it ended up costing about $100 worth of material from Home depot, and I think the only tool I really needed was a circular saw and a drill. I highly recommend using lots of wood glue on each wood joint, and pre-drilling screw holes on the outside piece of wood only, and then use the screw the tighten the wood joint together, and the wood glue will form a bond stronger than the wood itself. It makes the stand easier to build, and less "rickety" with age.
It might be a good idea to have 2 cross pieces (blue) for a 75 gal. Some people put a solid piece of plywood on the top, but for a typical glass standard size <180 gallon tank, I don't think its necessary. Most tanks put all the weight on the outside of the tank, and the glass base doesn't actually touch the stand. If your tank needs weight support in the center, use large nails, not screws, to fasten the cross pieces.
Also, buy a good level, and make sure the stand is ABSOLUTELY LEVEL (and the floor its going on for that matter) before putting the tank on it.
Good luck!
