A ladder-style bookshelf  

Great shelves and very nice...
Great shelves and very nice to see your workings in imperial measures (that's feet and inches to any 'proper' Europeans viewing)! Although I grew up with the metric system in the UK I still find imperial weights and measures somehow more instinctively 'right'

how many feet are in a gallon?
regarding the imperial versus the metric system, i suppose at some point the great american experiment will include a serious attempt at converting over to the more ubiquitous and logical system.
i remember back in probably the late 60s or early 70s there was some sort of push to move us in that direction, but it seemed rather feeble and short-lived. old habits die hard, you know.
even though the metric system is much more inherently rational and therefore much easier to compute, i myself will likely always buy my wood by the board-foot and order up my guinness by the pint.
oh, yeah ... on the shelf system: nice going, sdr!

As
Lisa says (on "The Simpsons"), "Springfield was the first American city to give up on the metric system. . ."
If Sweden could switch to driving on the right, and the UK could revamp their currency, you'd think the US could adopt the metric system. But (sadly) I wouldn't hold my breath. . .