I needed Base 10 blocks for large numbers, above the hundreds. I found that the thousand in traditional blocks was too large for use on desk tops, and they didn't offer ten or hundred thousand. So as a class we decided that:
a 100 flat with an "x" would model thousand
a 100 flat with "//" would model ten thousand
a 100 flat shaded in would model hundred thousand
The set includes blocks for both ones and thousand periods. I printed them on card stock for durability. My students loved them, and gave the kids just a little more support.