I needed to make hundreds of HST for a quilt. I used the grid method. I bought disposable cutting boards, ( thin but sturdy plastic) and my DH made a template to use for this. It had the grid drawn on it with small notches where the corners intersected and small holes where they intersected in the center of the grid. I could put this grid on the lighter fabric and mark all of the intersections. I then removed the grid and using a straight edge drew in the remaining lines. Here is a link to the grid method.
http://www.patchwork-and-quilting.co...triangles.html