I will re-attach the file (pg 512-513) that you posted in the Math section here, for other readers to refer to.
I will also attach a couple of example pages of how I have seen these done in tactile form.
I have never seen the thousandth block used in Grade 2 material before. In the books that I have worked with, even Grade 3 only shows up to the hundreds shape. Often they are referred to by name in the textbook as cubes, flats, rods, and ones. They are almost always taught with the use of manipulatives.
At the grade 2 level, I would do each of these as tactile graphics rather than devising a braille symbol or abbreviation.
I hope that you find this to be useful. Thanks for posting your question again here.
edited by betty.marshall on 2/28/2011