Months ago I threw together a very simple pot rack which has worked well enough, and then later saw this article which got me thinking about how I could expand my basic pot rack idea.  I really like the designs by nearby Atlas Industries:

...and the one by Argentinian Alejandro Sticotti:

I like the simplicity and elegance of the two designs - especially Sticotti's.  They are pretty pricey, though.  I also wanted to make something that was slightly more adjustable/modular.  And less expensive.  My shelves are for people who would love to have shelving systems like those above, but likely won't be able to afford them or have the space for them for at least a few years.  And Swedish alternatives are not an option.  My design is easier to produce, and with less expensive materials, but it isn't "cheap."

Looking at my current design, I want to make a few changes for the next version.

First, the crosspieces made of the walnut plywood that run the width of the unit bother me a bit.  Just too much.  It needs something a bit more delicate.

I think square steel tubing would be much better.  Certainly strong enough, but less wide, and dark metal with the walnut would look good and sort of recede into the background.  It should also make it easier to hang and obviate the need for the cleat.  It would also echo the size and shape of the pegs.

As for the pegs, I attached those using small dowels and holes drilled into both the frame and pegs.

It works well enough in this case, but the precision required to drill the holes so that the pegs are at exactly the correct height was harder than I thought, and since the location of the pegs affects the level-ness of the shelves, being a little bit off is a problem.  Not big amounts - 1/32" - but even that's noticable.  For the next version, I'm going to go a bit more Lincoln Log - the pegs on either side would be one solid piece, with corresponding notches on the uprights and pegs where they fit together.  Much easier to meet the requisite tolerances via  dados on the table saw than trying to drill identical 1/4" holes in dozens of different pieces.

In this version, the conduit doesn't pass through the uprights on either side.  This was another design consideration that made it much harder to build.  The holes in the uprights that accept the conduit had to be a precise depth, the conduit a precise length, and a hole drilled through the back side of the upright into the conduit for the set screw also had to line up perfectly.  As with the pegs, not too complicated, but those sorts of tolerances when it come to woodworking pose a challenge.  For the next version, the conduit will pass through at either end, but still be held in place with a set screw.  I also like the look of the o-rings.  This is a version in maple:

I'm also now working on designs for desktops and drawers that could be added to this modular system.  In addition, if you have a frame that can hold, say, 7 shelves, but want a larger space in the middle for taller books / sculpture, can easily remove a section of the conduit with a tubing cutter and customize the arrangement.  Then pop out a shelf and insert a desk.  Or a drawer.  Etc.