I want to make one to fit the top of a round table. Any idea what size to cut the squares? I guess they are typically 8 blocks by 8 so maybe for a 45"x45", i would cut 6" squares? Wondering how big are the squares cut for a bed-size??

The Maryquilts website has a Carpenter's Wheel made with 6 inch blocks. You can print or download the PDF file.
http://www.maryquilts.com/carpenter-star/ If you Google Carpenter Star quilt pattern, there are many more free ones on the internet. Mary's instructions do assume that you already know a good bit about quilt block construction & HST. Have FUN!!!!!

In doing your calculations, remember the seam allowances ... so your 6" squares would sew up as 5-1/2" and wo with an 8x8 block format, that'd mean your tabletopper would be 44" square, unless you added borders.

In reality, you can make your squares/HSTs as large or small as you like!
Carpenter's Squares can look really sweet done with 1-1/2" blocks!!!

Thank you both so much!! I think I will cut them 5" square and have room for a border. I enjoyed seeing the pics that had more than 3 fabrics in the mix! so many options! best part? it looks very fast and easy!!