Did you see the responses from your previous post?
http://www.quiltingboard.com/main-f1...k-t185399.html
I think you will get more help if you are more specific. Do you want the block to finish at 10.5", or do you want that to be the unfinished size? Many blocks have different names, but is this the one you want (the second on the page)?
http://www.quilting-in-america.com/ohio-star.html
If so, it is based on a 9-patch and is a variant of the Ohio Star. To make a 10.5" finished block, each patch in the 9-patch would finish at 3.5". This means you need to cut the squares at 4". You can follow the instructions here for the QST's -
http://www.patchwork-and-quilting.co...triangles.html. I agree with Holice (in your other post) that this block would be a nightmare for a group to work on unless all are accomplished quilters. Good luck!