It reads as if some more information is in order here, Erich. The fancy rack project that I'm trying to figure out is based on 2" x 2" x 0.065" (thickness) mild steel tubing, which are essentially used as the vertical supports in the design. There will be (10) of these vertical supports in the rack, (5) in front and (5) roughly 22" behind. The 1" x 1" square tubing in the design will be used to connect the front 2 x 2s to the rears and will also be used to bear the load as horizontal members in the design. So just imagine (10) 2 x 2 legs being linked together, both front to rear and side to side with 1 x 1 square tubing.
No doubt, there are racks out there that could be purchased, but this rack will be used to support some very expensive and odd-shaped audio/video equipment in a very large room, so the customer has a "custom" rack in mind. Normally, we would simply laminate a bunch of nice hardwood together and use the mortise and tenon techniques I was taught as a kid to construct a beautiful rack, but this customer wants a "hybrid" of steel and wood, so there you go.
Back to the rack "skeleton" of the design, I think that I understand what you're suggesting with the 1" x 1" ID steel tubing now. What you're suggesting is that we use what I would call a "sleeve" to feed the 1" x 1" OD tubing through. That's a very interesting idea, but one thing that gives me pause with that design is that the 1" x 1" ID sleeves would have to be pretty "square" in regard to the 2" x 2" uprights to make this work. In other words, the sleeves you've proposed would have to pass through the uprights -- square on all four sides -- for the horizontal members of the design to end up both square and horizontally level. This is a very good idea, but I'm not sure that our mag drill, as nicely as it works, can be lined in such a way that we're sure that the holes it cuts are at a perfect 90-degrees with respect to the 2 x 2s. I mean, the 1 x 1s you've linked me to have an inner dimension of 1.010" x 1.010," and 0.01" isn't a lot of "play," if you know what I mean.
Considering that the posts/legs in the design are are only 0.065" in thickness, there is clearly a risk of deformation in pressing a broach through round holes. Eight of the legs in the rack will be about 47.5" in length, so being able to support the steel surrounding the "intermediate" pass-through holes during arbor pressing would problematic, as well. Sorry for anything that sounds negative, but I'm simply typing as I think through the steps in your suggestion...
As for the broach itself, what type of steel blank would you suggest for fabricating such a tool? I've seen a couple of YT videos showing folks making their own steel "press broaches," but they don't really get into a lot details about the materials they started out with. I even saw one in which a guy made one out of rebar. He started out grinding the "rod" into a beveled shaped, cut perpendicular slots into the sides of the newly-formed square, heated the tool up with two propane torches and quenched the finished product in water. I suppose that this could work to press a limited number of holes, but my experience with rebar tells me that it wouldn't last very long. I've seen short blanks of M2 HSS for sale, but I also have no idea how hard that would be to bevel down and, more to the point, how long such a blank would have to be for such a broach?
I apologize for the eyestrain, but I suppose that goes with being a bona fide steel novice. Lots of questions...
