When you have the other leg seated, the threaded rods will extend father than you want them to. You'll want to mark them so they can be cut to length. Place a washer and a nut on each threaded rod, and then tighten down the nut to pull everything tight. Depending upon the wrench you are using, and how much longer the rod is than it needs to be, you may find it necessary to stack up a number of washers, so that the nut is positioned where the wrench can operate on it.
These sorts of things are usually glued and screwed, but it's actually the glue that holds them together - the screws just hold everything tight while the glue cures. Screwing into hardboard or 1/4" ply is an exercise in futility, so I just used glue, and used my two 4x4's as long clamps. It would have been a bit easier, if I'd done this before I'd rough-cut the 4x4's, but it worked out.
You're not the first person to say this! I'm half inclined to use the Lowes shed as a starting point for my own design. But I do think I'd feel better if I could work as an "aprentice" next to an "old master". Someone at work is going to put me in touch with a guy who builds sheds for a living, and apparently he's competitive with the prices @ Lowes and HD. The Lowes shed comes with a "Handman Package" that I don't want but would end up paying for, anyway. The "workbenches" were laughably flimsy.
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