- Place the butterfly square on your board to line up with the inch grid and the diagonal line.
- Draw a diagonal line on the butterflies making a two inch triangle.
- Place the small triangle of E right side down to line up with the inch grid then mark in a diagonal line on this triangle following the diagonal line on the board.
There is a link on the right to a video on sewing half-square triangles.
Even though the measurements I have give are generous my finished block ended up exactly the right size without trimming. If you are worried then make your measurements even more generous but make sure you match points and joins in your final block.
The instructions can be accessed from Google Docs.